Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash Flows From Operating Activities: [Abstract]
Net income	$ 616,325	$ 435,071	$ 500,685
Adjustments to reconcile net income to net cash provided by (used in) operating activities: [Abstract]
Provision for credit losses	(100,000)	222,592	44,000
Change in fair value of mortgage servicing rights due to market changes	(41,637)	79,524	53,517
Change in fair value of mortgage servicing rights due to principal payments	38,761	41,598	38,979
Net unrealized losses (gains) from derivative contracts	30,201	(59,253)	(25,936)
Share-based compensation	9,759	16,392	15,544
Depreciation and amortization	102,468	99,013	95,416
Net amortization of discounts and premiums	18,293	5,357	(16,984)
Net losses (gains) on financial instruments and other losses (gains), net	(67,446)	(15,949)	(583)
Net gain on mortgage loans held for sale	(70,464)	(114,545)	(40,402)
Mortgage loans originated for sale	(2,818,789)	(3,764,112)	(3,025,930)
Proceeds from sale of mortgage loans held for sale	2,939,522	3,817,475	3,035,600
Capitalized mortgage servicing rights	(31,132)	(31,209)	(35,128)
Change in trading and fair value option securities	(4,357,950)	(2,103,931)	(483,007)
Change in receivables	39,183	945,087	(740,868)
Change in other assets	(12,568)	1,739	18,955
Change in other liabilities	12,897	8,895	92,463
Net cash provided by (used in) operating activities	(3,692,577)	(416,256)	(473,679)
Cash Flows From Investing Activities: [Abstract]
Proceeds from maturities or redemptions of investment securities	33,865	46,992	60,128
Proceeds from maturities or redemptions of available for sale securities	3,500,081	2,695,067	1,841,069
Purchases of available for sale securities	(4,607,199)	(4,575,324)	(5,245,256)
Proceeds from sales of available for sale securities	622,881	384,507	1,211,718
Change in amount receivable on unsettled available for sale securities transactions	(10,406)	(6,357)	25,410
Loans originated, net of principal collected	2,853,326	(1,103,752)	(44,414)
Net payments or proceeds on derivative asset contracts	161,093	(121,130)	33,566
Net change in restricted equity securities	88,278	289,161	116,105
Proceeds from disposition of assets	165,040	73,135	62,576
Purchases of assets	(204,287)	(141,134)	(384,639)
Net cash provided by (used in) investing activities	2,602,672	(2,458,835)	(2,323,737)
Cash Flows From Financing Activities: [Abstract]
Net change in demand deposits, transaction deposits and savings accounts	5,360,979	8,773,433	2,252,936
Net change in time deposits	(262,800)	(250,721)	104,288
Net change in other borrowed funds	(1,269,241)	(5,091,026)	1,110,970
Repayment of subordinated debentures	(150,000)	0	0
Change in amount due on unsettled security purchases	(117,452)	63,521	(41,651)
Issuance of common and treasury stock, net	(4,874)	(4,933)	(7)
Net change in derivative margin accounts	(467,865)	(600,218)	(207,122)
Net payments or proceeds on derivative liability contracts	(79,962)	127,054	(33,622)
Repurchase of common stock	(117,938)	(75,830)	(129,483)
Dividends paid	(144,105)	(144,437)	(143,496)
Net cash provided by (used in) financing activities	2,746,742	2,796,843	2,912,813
Net increase (decrease) in cash and cash equivalents	1,656,837	(78,248)	115,397
Cash and cash equivalents at beginning of period	1,180,573	1,258,821	1,143,424
Cash and cash equivalents at end of period	2,837,410	1,180,573	1,258,821
Supplemental Cash Flow Information: [Abstract]
Cash paid for interest	68,775	160,288	417,070
Cash paid for taxes	135,331	136,181	87,361
Net loans and bank premises transferred to repossessed real estate and other assets	8,320	85,323	10,665
Increase in U.S. government guaranteed loans eligible for repurchase	87,087	290,977	91,634
Increase in receivables from conveyance of GNMA OREO	6,376	11,322	28,669
Right-of-use assets obtained in exchange for operating lease liabilities	$ 40,798	$ 16,177	$ 62,755