Consolidated Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Cash Flows [Abstract]
Net Income (Loss) Attributable to Parent	$ 61,598	$ 123,394	$ (10,206)
Depreciation, Amortization and Accretion, Net	14,101	11,823	10,589
Debt Securities, Realized Gain (Loss)	97,237	(22,899)	0
Amortization of Deferred Loan Origination Fees, Net	(3,777)	(17,506)	0
Gain (Loss) on Sales of Consumer Loans	(36,537)	(33,468)	(22,254)
Share-based Payment Arrangement, Noncash Expense	19,183	6,772	5,705
Provision for Loan and Lease Losses	(4,483)	16,147	98,315
Deferred Income Tax Expense (Benefit)	10,419	42,023	8,291
Other Noncash Income (Expense)	9,728	6,101	9,559
Payments for Origination and Purchases of Loans Held-for-sale	(355,617)	(292,386)	(220,529)
Proceeds from Sale of Other Loans Held-for-sale	391,438	328,253	241,277
Increase (Decrease) in Accrued Interest Receivable, Net	(7,128)	(6,889)	(3,453)
Increase (Decrease) in Other Operating Assets	(47,628)	(28,205)	(6,036)
Increase (Decrease) in Amount Due to Whole Loan Buyer	5,413	5,898	8,560
Increase (Decrease) in Other Operating Liabilities	64,427	(684)	19,300
Net Cash Provided by (Used in) Operating Activities	218,374	138,374	139,118
Payments to Acquire Loans Held-for-investment	(1,487,103)	(1,322,102)	(1,062,692)
Proceeds from Principal Repayments on Loans and Leases Held-for-investment	1,015,646	868,619	731,325
Payments to Acquire Property, Plant, and Equipment	(8,875)	(14,559)	(8,548)
Payments for Software	(17,348)	(3,385)	(3,473)
Net Cash Provided by (Used in) Investing Activities	(497,680)	(471,427)	(343,388)
Proceeds from Long-term Lines of Credit	144,000	481,000	441,240
Proceeds from Issuance Initial Public Offering	60,479	0	0
Proceeds from Issuance of Secured Debt	249,951	863,165	360,001
Repayments of Long-term Lines of Credit	(169,000)	(549,780)	(323,460)
Repayments of Secured Debt	0	(424,837)	(237,544)
Repayments of Long-term Capital Lease Obligations	(270)	(259)	(397)
Payments of Financing Costs	0	(862)	(5,874)
Proceeds from (Repurchase of) Equity	1,112	(354)	(3,278)
Net Cash Provided by (Used in) Financing Activities	286,272	368,073	230,688
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	6,966	35,020	26,418
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, beginning of period	129,175	94,155	67,737
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, end of period	136,141	129,175	94,155
Total Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	129,175	129,175	67,737
Income Taxes Paid, Net	2,933	20,440	4,402
Interest Paid, Including Capitalized Interest, Operating and Investing Activities	58,038	42,428	31,064
Operating Lease, Payments	12,759	0	0
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	59,564	0	0
Dividends, Preferred Stock, Paid-in-kind	37,456	0	0
Other Significant Noncash Transaction, Value of Consideration Received	0	0	1,076
Noncash or Part Noncash Acquisition, Fixed Assets Acquired	$ 687	$ 544	$ 543