Class of Stock [Axis] Series A Preferred Stock [Member] Series B Preferred Stock [Member] Equity Components [Axis] Common Stock Retained Earnings Accumulated Other Comprehensive Loss Income Statement Location [Axis] Direct Mail Revenues [Member] Convenience Fee Revenue [Member] Recoveries on previously charged-off contracts [Member] Sales Tax Refunds [Member] Other Income [Member] Financing Receivables, Period Past Due [Axis] Financing Receivables, 31 - 60 Days Past Due [Member] Financing Receivables, 61 - 90 Days Past Due [Member] Financing Receivables, 91+ Days Past Due [Member] Financial Instrument [Axis] CPS 2014-A [Member] CPS 2014-B [Member] CPS 2014-C [Member] CPS 2014-D [Member] CPS 2015-A [Member] CPS 2015-B [Member] CPS 2015-C [Member] CPS 2016-A [Member] CPS 2016-B [Member] CPS 2016-C [Member] CPS 2016-D [Member] CPS 2017-A [Member] CPS 2017-B [Member] CPS 2017-C [Member] CPS 2017-D [Member] CPS 2018-A [Member] CPS 2018-B [Member] CPS 2018-C [Member] CPS 2018-D [Member] CPS 2019-A [Member] Securitization Trust Debt [Member] CreditFacility [Axis] Warehouse lines of credit [Member] Warehouse lines of credit (2) [Member] Warehouse lines of credit (3) [Member] Residual interest financing [Member] Subordinated renewable notes [Member] Warehouse Lines of Credit [Member] Long-term Debt, Type [Axis] Securities Financing Transaction [Axis] Contractual Balance [Member] Measurement Basis [Axis] Fair Value [Member] FairValueByFairValueHierarchyLevel [Axis] Level 3 [Member] Level 1 [Member] Level 2 [Member] Share Repurchase Program [Axis] Common Stock [Member] Transaction Type [Axis] Open Market Purchases [Member] Shares redeemed upon net exercise of stock options Other Purchases [Member] Measurement Input Type [Axis] Discount Rate [Member] Cumulative Net Losses [Member] FairValueByAssetClass [Axis] Carrying Value [Member] Document And Entity Information Entity Registrant Name Entity Central Index Key Document Type Trading Symbol Document Period End Date Amendment Flag Current Fiscal Year End Date Entity a Well-known Seasoned Issuer Entity a Voluntary Filer Entity's Reporting Status Current Entity Filer Category Entity Emerging Growth Company Entity Small Business Entity Shell Company Entity Public Float Entity Common Stock, Shares Outstanding Document Fiscal Period Focus Document Fiscal Year Focus Statement [Table] Statement [Line Items] ASSETS Cash and cash equivalents Restricted cash and equivalents Finance receivables Less: Allowance for finance credit losses Finance receivables, net Finance receivables measured at fair value Furniture and equipment, net Deferred tax assets, net Accrued interest receivable Other assets Total LIABILITIES AND SHAREHOLDERS' EQUITY Liabilities Accounts payable and accrued expenses Warehouse lines of credit Residual interest financing Securitization trust debt Subordinated renewable notes Total COMMITMENTS AND CONTINGENCIES Shareholders' Equity Preferred stock Common stock, no par value; authorized 75,000,000 shares; 22,134,142 and 22,421,688 shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively Retained earnings Accumulated other comprehensive loss Total stockholders' equity Total liabilities and stockholders' equity Preferred stock, par value (in dollars per share) Preferred stock, authorized Preferred stock, issued Common stock, no par value (in dollars per share) Common stock, authorized Common stock, issued Common stock, outstanding Income Statement [Abstract] Revenues: Interest income Other income Total revenues Expenses: Employee costs General and administrative Interest Provision for credit losses Marketing Occupancy Depreciation and amortization Total operating expenses Income before income tax expense Income tax expense Net income Earnings per share: Basic (in dollars per share) Diluted (in dollars per share) Number of shares used in computing earnings per share: Basic (in shares) Diluted (in shares) Statement of Comprehensive Income [Abstract] Net income Other comprehensive income/(loss); change in funded status of pension plan Comprehensive income Statement of Cash Flows [Abstract] Cash flows from operating activities: Adjustments to reconcile net income to net cash provided by operating activities: Accretion of deferred acquisition fees and origination costs Net interest income accretion on fair value receivables Amortization of deferred financing costs Stock-based compensation expense Changes in assets and liabilities: Accrued interest receivable Deferred tax assets, net Other assets Accounts payable and accrued expenses Net cash provided by operating activities Cash flows from investing activities: Purchases of finance receivables held for investment Payments received on finance receivables held for investment Purchases of finance receivables measured at fair value Payments received on finance receivables at fair value Change in repossessions held in inventory Purchase of furniture and equipment Net cash used in investing activities Cash flows from financing activities: Proceeds from issuance of securitization trust debt Proceeds from issuance of subordinated renewable notes Payments on subordinated renewable notes Net advances of warehouse lines of credit Repayment of securitization trust debt Payment of financing costs Purchase of common stock Exercise of options and warrants Net cash provided by (used in) financing activities Increase (decrease) in cash and cash equivalents Cash and restricted cash at beginning of period Cash and restricted cash at end of period Supplemental disclosure of cash flow information: Cash paid during the period for: Interest Income taxes Non-cash financing activities: Right-of-use asset, net Lease liability Deferred office rent Beginning balance, shares Beginning balance, value Common stock issued upon exercise of options and warrants, shares Common stock issued upon exercise of options and warrants, value Repurchase of common stock, shares Repurchase of common stock, value Stock-based compensation Pension benefit obligation Ending balance, shares Ending balance, value Accounting Policies [Abstract] Summary of Significant Accounting Policies Receivables [Abstract] Finance Receivables Securitization Trust Debt Securitization Trust Debt Debt Disclosure [Abstract] Debt Banking and Thrift [Abstract] Interest Income and Interest Expense Earnings Per Share [Abstract] Earnings Per Share Income Tax Disclosure [Abstract] Income Taxes Commitments and Contingencies Disclosure [Abstract] Legal Proceedings Retirement Benefits [Abstract] Employee Benefits Fair Value Disclosures [Abstract] Fair Value Measurements Description of Business Basis of Presentation Use of Estimates Finance Receivables Measured at Fair Value Other Income Leases Stock-based Compensation Purchases of Company Stock Reclassifications Financial Covenants Provision for Contingent Liabilities Adoption of New Accounting Standards Schedule of other Income Operating lease table Finance lease table Maturities of lease liabilities Schedule of stock option activity Schedule of purchases of company stock Schedule of financial receivables Schedule of delinquency status of finance receivables Schedule of allowance for credit losses Schedule of allowance for losses on repossessed inventory Schedule of securitization trust debt Schedule of debt outstanding Schedule of interest income Schedule of interest expense Schedule of computation of basic and diluted earnings per share Schedule of net periodic cost (benefit) Schedule of reconciliation of the finance receivables measured at fair value on a recurring basis Schedule of finance receivables to their contractual balances Schedule of level 3 fair value measurements Schedule of delinquency status of finance receivables measured at fair value Schedule of estimated fair values of financial assets and liabilities Other income for the period Operating Leases Operating lease right-of-use assets Less: Accumulated amortization right-of-use assets Operating lease right-of-use assets, net Operating lease liabilities Finance Leases Property and equipment, at cost Less: Accumulated depreciation Property and equipment, net Finance lease liabilities Maturities of lease liabilities 2019 (excluding the three months ended March 31, 2019) 2020 2021 2022 2023 Thereafter Total undiscounted lease payments Less amounts representing interest Lease Liability Operating lease cost Finance lease cost Total lease cost Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases Operating cash flows from finance leases Financing cash flows from finance leases Number of Shares Outstanding options, beginning balance Granted Exercised Forfeited Outstanding options, ending balance Options exercisable at the end of period Weighted Average Exercise Price Outstanding options, beginning balance Granted Exercised Forfeited Outstanding options, ending balance Options exercisable at the end of period Weighted Average Remaining Contractual Term Weighted average remaining contractual term options outstanding Weighted average remaining contractual term options exercisable Total stock purchases Average price for total stock purchases Stock based compensation costs Unrecognized stock-based compensation costs Unrecognized stock-based compensation costs amortization period Aggregate intrinsic value outstanding Aggregate intrinsic value exercisable Options Exercised Total intrinsic value of options exercised Shares available for future grants Lease right-of-use asset Weighted Average Discount Rate Operating lease Automobile finance receivables, net of unearned interest Unearned acquisition fees and originations costs Finance Receivables Financial Asset, Period Past Due [Axis] Current Finance receivables Allowance for credit losses, beginning balance Charge-offs Recoveries Allowance for credit losses, ending balance Gross balance of repossessions in inventory Allowance for losses on repossessed inventory Net repossessed inventory included in other assets Finance receivables Debt Securities, Held-to-maturity [Table] Schedule of Held-to-maturity Securities [Line Items] "Securitization trust debt," and components of debt Final Scheduled Payment Date Receivables Pledged at end of period Initial Principal Outstanding Principal Weighted Average Contractual Interest Rate Expected finance receivable payments 2019 Expected finance receivable payments 2020 Expected finance receivable payments 2021 Expected finance receivable payments 2022 Expected finance receivable payments 2023 Expected finance receivable payments 2024 Debt issuance costs Restricted cash Credit Facility [Axis] Total debt outstanding Interest rate Interest rate Maturity date Unamortized debt issuance costs Credit line maximum borrowing amount Credit line expiration date Components of interest income Interest on finance receivables Interest on finance receivables at fair value Other interest income Interest income Total interest expense Weighted average number of common shares outstanding during the period used to compute basic earnings per share Incremental common shares attibutable to exercise of outstanding options and warrants Weighted average number of common shares used to compute diluted earnings per share Antidilutive common stock equivalents Unrecognized tax benefits Deferred tax asset U.S. federal deferred tax assets State deferred tax assets Effective income tax rate Components of net periodic cost (benefit) Service cost Interest cost Expected return on assets Amortization of transition (asset)/obligation Amortization of net (gain)/loss Net periodic cost (benefit) Plan contribution Finance receivables, beginning balance Finance receivables at fair value acquired during period Payments received on finance receivables at fair value Net interest income accretion on fair value receivables Mark to fair value Finance receivables, ending balance Fair Value, by Balance Sheet Grouping [Table] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value Hierarchy and NAV [Axis] Unobservable Inputs Finance receivables measured at fair value current Finance receivables measured at fair value Fair Value, Recurring and Nonrecurring [Table] Asset Class [Axis] Assets: Cash and cash equivalents Restricted cash and equivalents Finance receivables, net Accrued interest receivable Liabilities: Warehouse lines of credit Accrued interest payable Residual interest financing Securitization trust debt Subordinated renewable notes Finance receivables related to reposessed vehicles in inventory Valuation adjustment, loss allowance Recovery rate Estimated fair value and carrying amount of repossed inventory Allowance for losses on repossessed inventory [Table Text Block] Cash paid (received) during the period for: abstract Change in repossessions in inventory Deferred office rent. Lease liability. Other income [Policy Text Block] Purchases of finance receivables held for investment Residual interest financing. Right of us asset net. Schedule of delinquency status of finance receivables measured at fair value [Table Text Block] Tabular disclousre information about finance receivables to their contractual balances [Table Text Block] Represent Information about direct mail revenues. Represent Information about convenience fee. Represent Information about recoveries. Represent Information about sales tax refunds. Accumulated amortization right of use assets. Finance leaes [Abstract] Cash paid for amounts included in the measurement of lease liabilities [Abstract] Financing cash flows from finance leases. Weighted Average Remaining Contractual Term [Abstract] Represent Information by major type of debt and equity security. Represent Information by major type of debt and equity security. Represent Information by major type of debt and equity security. Represent Information by major type of debt and equity security. Represent Information by major type of debt and equity security. Represent Information by major type of debt and equity security. CPS 2015C Member Represent Information by major type of debt and equity security. Represent Information by major type of debt and equity security. Represent Information by major type of debt and equity security. Represent Information by major type of debt and equity security. Represent Information by major type of debt and equity security. Represent Information by major type of debt and equity security. Represent Information by major type of debt and equity security. Represent Information by major type of debt and equity security. Represent Information by major type of debt and equity security. Final Scheduled Payment Date Securitization Trust Debt Initial Principal Collateralized debt obligation backed by, for example, but not limited to, pledge, mortgage or other lien on the entity's assets. Expected finance receivable payments year one Expected finance receivable payments year two Expected finance receivable payments year three Expected finance receivable payments year four Expected finance receivable payments year five Expected finance receivable payments year six. Information by type of credit facility. Credit facilities provide warehouse credit facility borrowing. Information by type of credit facility. Credit facilities provide warehouse credit facility borrowing. Information by type of credit facility. Credit facilities provide warehouse credit facility borrowing. Subordinated Renewable Notes. Information by type of credit facility. Credit facilities provide warehouse credit facility borrowing. Represent Information contractual balance. Represent Information about measurement input cumulative net lossese. Represent Information about carrying value. Schedule of other Income [Table Text Block] Operating lease right-of-use assets before accumulated amortization Amount of lessee's right to use underlying asset under finance lease before accumulated depreciation Amount of lessee's right to use underlying asset under finance lease accumulated depreciation Maturities of lease liabilities [Abstract] Amount of interest for operating leases having an initial or remaining non-cancelable letter. Finance lease cost Finance receivables measured at fair value current Finance receivables measured at fair value past due Residual interest financing fair value disclosure Restricted cash and equivalents fair value disclosure Accrued interest receivable fair value disclosure Accrued interest payable fair value disclosure Finance receivables recovery rate Finance receivables fair value inputs unobservable inputs Financing Receivable, Allowance for Credit Loss Loans and Leases Receivable, Net Amount Assets Liabilities [Default Label] Stockholders' Equity Attributable to Parent Liabilities and Equity Revenues Direct Operating Costs Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Increase (Decrease) in Accrued Interest Receivable, Net Increase (Decrease) in Prepaid Expense and Other Assets Increase (Decrease) in Other Operating Assets Increase (Decrease) in Accounts Payable and Accrued Liabilities Net Cash Provided by (Used in) Operating Activities PurchasesOfFinanceReceivablesHeldForInvestment Payments for (Proceeds from) Loans Receivable ChangeInRepossessionsInInventory Payments to Acquire Property, Plant, and Equipment Net Cash Provided by (Used in) Investing Activities Repayment of Long-term Debt, Long-term Lease Obligation, and Capital Security Repayments of Secured Debt Payments of Financing Costs Payments for Repurchase of Common Stock Net Cash Provided by (Used in) Financing Activities Cash and Cash Equivalents, Period Increase (Decrease) Restricted Cash and Cash Equivalents, Current Interest Paid, Excluding Capitalized Interest, Operating Activities RightOfUseAssetNet Document And Entity Information [Default Label] Shares, Outstanding Stock Repurchased During Period, Value Long-term Debt [Text Block] Allowance for losses on repossessed inventory FinanceLeaseRightOfUseAssetAccumulatedDepreciation Finance Lease, Right-of-Use Asset Operating Leases, Future Minimum Payments Due OperatingLeasesFutureMinimumPaymentsDueInterest Lease, Cost Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Financing Receivable, Past Due Accounts Receivable, Allowance for Credit Loss, Writeoff Financing Receivable, Nonaccrual Debt Instrument, Description of Variable Rate Basis Proceeds from Collection of Finance Receivables Finance Lease, Interest Expense FinancingReceivableFairValueRecordedInvestmentPastDue Cash and Cash Equivalents, Fair Value Disclosure RestrictedCashAndEquivalentsFairValueDisclosure AccruedInterestReceivableFairValueDisclosure Lines of Credit, Fair Value Disclosure ResidualInterestFinancingFairValueDisclosure Servicing Liability at Fair Value, Amount Financial Liabilities Fair Value Disclosure