CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Operating activities
Net income	$ 581,391	$ 469,014	$ 1,160,513
Adjustments to reconcile net income to net cash used in operating activities:
Provisions for credit losses	345,463	633,453	(32,957)
Deferred tax provision (benefit)	(23,224)	(93,670)	55,372
Amortization of brokered deposit placement fee	11,681	12,904	15,516
Amortization of Secured Borrowing Facility upfront fee	2,869	2,634	2,415
Amortization of deferred loan origination costs and loan premium/(discounts), net	12,583	14,804	16,103
Net amortization of discount on investments	(2,726)	103	7,310
Reduction of tax indemnification receivable	2,816	5,231	10,445
Depreciation of premises and equipment	17,811	17,331	16,043
Acquired intangible assets impairment and amortization expense	66,364	7,779	0
Stock-based compensation expense	36,380	34,461	30,649
Unrealized (gains) losses on derivative and hedging activities, net	(341)	269	23,249
Gains on sale of loans, net	(160,290)	(327,750)	(548,315)
(Gains) losses on securities, net	(2,678)	60,267	(39,096)
Acquisition transaction costs, net	952	2,603	0
Other adjustments to net income, net	16,212	14,213	15,686
Changes in operating assets and liabilities:
Increase in accrued interest receivable	(1,054,071)	(819,958)	(743,757)
Increase in trading investments	0	(5,117)	0
Increase in non-marketable securities	(1,256)	(2,050)	(9,969)
(Increase) decrease in other interest-earning assets	1,933	(1,507)	33,219
Increase in other assets	(38,902)	(23,472)	(123,268)
Increase (decrease) in income tax payable, net	36,723	(15,063)	72,191
Increase (decrease) in accrued interest payable	33,480	24,986	(13,672)
Increase (decrease) in other liabilities	(27,807)	(6,473)	2,801
Total adjustments	(726,028)	(464,022)	(1,210,035)
Total net cash (used in) provided by operating activities	(144,637)	4,992	(49,522)
Investing activities
Loans acquired and originated	(6,452,199)	(6,081,389)	(5,511,845)
Net proceeds from sales of loans held for investment and loans held for sale	3,198,502	3,459,527	4,642,505
Proceeds from FFELP Loan claim payments	50,145	33,197	19,386
Net decrease in loans held for investment and loans held for sale (other than loans acquired and originated, and loan sales)	3,046,064	3,586,825	3,845,990
Purchases of available-for-sale securities	(105,970)	(753,129)	(1,257,129)
Proceeds from sales and maturities of available-for-sale securities	265,652	960,015	865,766
Purchase of subsidiary, net of cash acquired	(14,654)	(127,654)	0
Total net cash (used in) provided by investing activities	(12,460)	1,077,392	2,604,673
Financing activities
Brokered deposit placement fee	(7,841)	(11,170)	(12,565)
Net increase (decrease) in certificates of deposit	953,412	130,109	(2,130,728)
Net increase (decrease) in other deposits	(770,485)	570,147	393,306
Borrowings collateralized by loans in securitization trusts - issued	1,135,036	572,640	1,585,125
Borrowings collateralized by loans in securitization trusts - repaid	(1,154,269)	(1,278,183)	(1,143,738)
Fees paid on Secured Borrowing Facility	(2,868)	(2,833)	(2,846)
Unsecured debt issued	0	0	492,135
Unsecured debt repaid	0	0	(202,784)
Preferred stock dividends paid	(17,705)	(9,029)	(4,736)
Common stock dividends paid	(101,233)	(112,961)	(60,462)
Common stock repurchased	(350,264)	(713,197)	(1,530,683)
Net cash used in financing activities	(316,232)	(854,892)	(2,619,516)
Net increase (decrease) in cash, cash equivalents and restricted cash	(473,329)	227,492	(64,365)
Cash, cash equivalents and restricted cash at beginning of year	4,772,836	4,545,344	4,609,709
Cash, cash equivalents and restricted cash at end of year	4,299,507	4,772,836	4,545,344
Cash disbursements made for:
Interest	963,260	482,974	359,684
Income taxes paid	191,690	272,940	261,473
Income taxes refunded	(8,201)	(2,043)	(8,614)
Reconciliation of the Consolidated Statements of Cash Flows to the Consolidated Balance Sheets:
Cash and cash equivalents	4,149,838	4,616,117	4,334,603
Restricted cash	149,669	156,719	210,741
Total cash, cash equivalents and restricted cash	4,299,507	4,772,836	4,545,344
Collateralized Securities
Financing activities
Issuance costs for unsecured debt offering	(15)	(40)	0
Unsecured Debt
Financing activities
Issuance costs for unsecured debt offering	$ 0	$ (375)	$ (1,540)