CONSOLIDATED STATEMENTS OF CASH FLOWS	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Operating activities
Net income	$ 469,014,000	$ 1,160,513,000	$ 880,690,000
Adjustments to reconcile net income to net cash used in operating activities:
Provisions for credit losses	633,453,000	(32,957,000)	93,133,000
Deferred tax provision (benefit)	(93,670,000)	55,372,000	72,776,000
Amortization of brokered deposit placement fee	12,904,000	15,516,000	19,401,000
Amortization of Secured Borrowing Facility upfront fee	2,634,000	2,415,000	2,976,000
Amortization of deferred loan origination costs and loan premium/(discounts), net	14,804,000	16,103,000	24,152,000
Net amortization of discount on investments	103,000	7,310,000	6,350,000
Reduction of tax indemnification receivable	5,231,000	10,445,000	9,066,000
Depreciation of premises and equipment	17,331,000	16,043,000	15,066,000
Acquired intangible assets amortization expense	7,779,000	0	0
Stock-based compensation expense	34,461,000	30,649,000	36,464,000
Unrealized (gains) losses on derivative and hedging activities, net	269,000	23,249,000	(10,333,000)
Gains on sale of loans, net	(327,750,000)	(548,315,000)	(238,315,000)
(Gains) losses on securities, net	60,267,000	(39,096,000)	(4,372,000)
Acquisition transaction costs, net	2,603,000	0	0
Gain on sale of Upromise subsidiary, net	0	0	(11,331,000)
Other adjustments to net income, net	14,213,000	15,686,000	13,182,000
Changes in operating assets and liabilities:
Increase in accrued interest receivable	(819,958,000)	(743,757,000)	(876,703,000)
Increase in trading investments	5,117,000	0	0
Increase in non-marketable securities	(2,050,000)	(9,969,000)	(839,000)
(Increase) decrease in other interest-earning assets	(1,507,000)	33,219,000	9,690,000
Increase in other assets	(23,472,000)	(123,268,000)	(50,454,000)
Increase (decrease) in income tax payable, net	(15,063,000)	72,191,000	(45,611,000)
Increase (decrease) in accrued interest payable	24,986,000	(13,672,000)	(14,602,000)
Decrease in Upromise member accounts due to sale	0	0	(193,840,000)
Increase (decrease) in other liabilities	(6,473,000)	2,801,000	80,785,000
Total adjustments	(464,022,000)	(1,210,035,000)	(1,063,359,000)
Total net cash provided by (used in) operating activities	4,992,000	(49,522,000)	(182,669,000)
Investing activities
Loans acquired and originated	(6,081,389,000)	(5,511,845,000)	(5,378,283,000)
Net proceeds from sales of loans held for investment	3,459,527,000	4,642,505,000	3,875,737,000
Proceeds from claim payments	33,197,000	19,386,000	28,709,000
Net decrease in loans held for investment	3,586,825,000	3,845,990,000	3,832,991,000
Purchases of available-for-sale securities	(753,129,000)	(1,257,129,000)	(2,083,261,000)
Proceeds from sales and maturities of available-for-sale securities	960,015,000	865,766,000	654,515,000
Purchase of subsidiary, net of cash acquired	(127,654,000)	0	0
Proceeds from the sale of Upromise subsidiary, net	0	0	16,922,000
Total net cash provided by investing activities	1,077,392,000	2,604,673,000	947,330,000
Financing activities
Brokered deposit placement fee	(11,170,000)	(12,565,000)	(4,810,000)
Net increase (decrease) in certificates of deposit	130,109,000	(2,130,728,000)	(2,428,094,000)
Net increase in other deposits	570,147,000	393,306,000	704,382,000
Borrowings collateralized by loans in securitization trusts - issued	572,640,000	1,585,125,000	1,338,641,000
Borrowings collateralized by loans in securitization trusts - repaid	(1,278,183,000)	(1,143,738,000)	(1,003,327,000)
Repayment of borrowings under Secured Borrowing Facility	0	0	(289,230,000)
Fees paid - Secured Borrowing Facility	(2,833,000)	(2,846,000)	(3,256,000)
Unsecured debt issued	0	492,135,000	495,000,000
Unsecured debt repaid	0	(202,784,000)	0
Preferred stock dividends paid	(9,029,000)	(4,736,000)	(9,734,000)
Repurchase of Series B Preferred Stock	0	0	(68,055,000)
Common stock dividends paid	(112,961,000)	(60,462,000)	(46,351,000)
Common stock repurchased	(713,197,000)	(1,530,683,000)	(558,167,000)
Net cash used in financing activities	(854,892,000)	(2,619,516,000)	(1,875,712,000)
Net increase (decrease) in cash, cash equivalents and restricted cash	227,492,000	(64,365,000)	(1,111,051,000)
Cash, cash equivalents and restricted cash at beginning of year	4,545,344,000	4,609,709,000	5,720,760,000
Cash, cash equivalents and restricted cash at end of year	4,772,836,000	4,545,344,000	4,609,709,000
Cash disbursements made for:
Interest	482,974,000	359,684,000	517,444,000
Income taxes paid	272,940,000	261,473,000	248,122,000
Income taxes refunded	(2,043,000)	(8,614,000)	(6,219,000)
Reconciliation of the Consolidated Statements of Cash Flows to the Consolidated Balance Sheets:
Cash and cash equivalents	4,616,117,000	4,334,603,000	4,455,292,000
Restricted cash	156,719,000	210,741,000	154,417,000
Total cash, cash equivalents and restricted cash	4,772,836,000	4,545,344,000	4,609,709,000
Collateralized Securities
Financing activities
Issuance costs for collateralized borrowings and unsecured debt offering	(40,000)	0	(1,402,000)
Unsecured Debt
Financing activities
Issuance costs for collateralized borrowings and unsecured debt offering	$ (375,000)	$ (1,540,000)	$ (1,309,000)