Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating activities:
Net income	$ 171,903	$ 120,747
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	1,616	1,409
Provision for loan losses	2,427	7,724
Gain on sale of securities		(441)
Gain on sale of loans	(82,755)	(67,748)
Proceeds from sales of loans	44,276,199	63,058,544
Loans and participations originated and purchased for sale	(44,463,275)	(64,230,337)
Change in servicing rights for paydowns and fair value adjustments	526	13,021
Net change in:
Mortgage loans in process of securitization	(295,294)	(104,830)
Other assets and receivables	(1,209)	(20,576)
Other liabilities	3,007	12,314
Other	(980)	1,947
Net cash (used in) operating activities	(387,835)	(1,208,226)
Investing activities:
Net change in securities purchased under agreements to resell	657	107
Purchases of available for sale securities	(195,206)	(434,331)
Proceeds from the sale of available for sale securities	34,469	4,347
Proceeds from calls, maturities and paydowns of available for sale securities	128,502	441,181
Purchases of loans	(312,992)	(236,358)
Net change in loans receivable	(16,240)	(1,614,787)
Proceeds from sale of loans receivable	262,086
Purchase of FHLB stock	(111)	(50,854)
Proceeds from sale of FHLB stock		567
Proceeds from sale of mortgage servicing rights	438
Purchases of premises and equipment	(3,281)	(1,430)
Cash (paid) received in deconsolidation of subsidiary	(464)
Purchase of limited partnership interests and other tax credits	(12,149)	(2,074)
Other investing activities	404	(730)
Net cash (used in) investing activities	(113,887)	(1,894,362)
Financing activities:
Net change in deposits	1,537,148	1,606,572
Proceeds from borrowings	28,803,270	31,577,468
Repayment of borrowings	(29,342,391)	(30,143,465)
Proceeds from notes payable		2,759
Proceeds from issuance of preferred stock	191,084
Redemption of preferred stock	(41,625)
Payments of contingent consideration		(501)
Dividends	(22,916)	(17,752)
Net cash provided by financing activities	1,124,570	3,025,081
Net Change in Cash and Cash Equivalents	622,848	(77,507)
Cash and Cash Equivalents, Beginning of Period	179,728	506,709
Cash and Cash Equivalents, End of Period	802,576	429,202
Additional Cash Flows Information:
Interest paid	23,049	57,940
Income taxes paid	57,692	$ 35,522
Transfer of loans from loans receivable to loans held for sale	$ 131,563