Consolidated Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities
Net income	$ 1,918,080	$ 1,408,306	$ 1,315,114
Adjustments to reconcile net income to net cash provided by operating activities
Provision for credit losses	132,000	168,000	190,000
Depreciation and amortization of premises and equipment	104,864	109,587	106,996
Amortization of capitalized servicing rights	49,619	56,172	50,982
Amortization of core deposit and other intangible assets	24,522	31,366	42,613
Provision for deferred income taxes	15,857	400,790	174,013
Asset write-downs	24,774	15,429	21,036
Net gain on sales of assets	(23,503)	(53,467)	(63,222)
Net change in accrued interest receivable, payable	(7,162)	(17,896)	(12,282)
Net change in other accrued income and expense	13,436	(201,981)	60,263
Net change in loans originated for sale	(150,695)	711,657	(665,649)
Net change in trading account assets and liabilities	(11,940)	153,972	(36,453)
Net cash provided by operating activities	2,089,852	2,781,935	1,183,411
Cash flows from investing activities
Proceeds from sales of investment securities Available for sale	418	534,160	63,513
Proceeds from sales of investment securities equity and other	650,858	178,468	94,749
Proceeds from maturities of investment securities Available for sale	1,997,263	2,131,118	2,309,208
Proceeds from maturities of investment securities Held to maturity	478,172	528,585	609,080
Purchases of investment securities Available for sale	(12,494)	(251,185)	(3,562,711)
Purchases of investment securities Held to maturity	(444,703)	(1,425,690)	(214,791)
Purchases of investment securities equity and other	(834,856)	(132,378)	(1,808)
Net (increase) decrease in loans and leases	(475,895)	1,931,492	(2,952,129)
Net (increase) decrease in interest-bearing deposits at banks	(3,026,294)	(78,265)	2,593,712
Capital expenditures, net	(97,676)	(78,966)	(107,693)
Net decrease in loan servicing advances	307,252	37,761	170,141
Other, net	47,904	19,825	277,961
Net cash provided (used) by investing activities	(1,410,051)	3,394,925	(720,768)
Cash flows from financing activities
Net increase (decrease) in deposits	(2,272,505)	(3,075,322)	3,554,673
Net increase (decrease) in short-term borrowings	4,223,279	11,657	(1,937,105)
Proceeds from long-term borrowings	1,773,189	2,145,950
Payments on long-term borrowings	(1,459,081)	(3,433,440)	(1,119,898)
Purchases of treasury stock	(2,194,396)	(1,205,905)	(641,334)
Dividends paid — common	(510,382)	(457,402)	(441,891)
Dividends paid — preferred	(72,521)	(72,734)	(81,270)
Redemption of Series D preferred stock			(500,000)
Other, net	17,167	10,675	161,691
Net cash used by financing activities	(495,250)	(6,076,521)	(510,134)
Net increase (decrease) in cash, cash equivalents and restricted cash	184,551	100,339	(47,491)
Cash, cash equivalents and restricted cash at beginning of period	1,420,888	1,320,549	1,368,040
Cash, cash equivalents and restricted cash at end of period	1,605,439	1,420,888	1,320,549
Supplemental disclosure of cash flow information
Interest received during the period	4,568,991	4,155,723	3,903,374
Interest paid during the period	516,230	405,290	498,951
Income taxes paid during the period	375,116	494,205	276,866
Supplemental schedule of noncash investing and financing activities
Real estate acquired in settlement of loans	72,408	121,292	124,033
Securitization of residential mortgage loans allocated to Available-for-sale investment securities	22,448	36,747	24,233
Securitization of residential mortgage loans allocated to capitalized servicing rights	$ 365	$ 422	248
Series F Preferred Stock [Member]
Cash flows from financing activities
Proceeds from issuance of Series F preferred stock			$ 495,000