Consolidated Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities
Net income	$ 1,315,114	$ 1,079,667	$ 1,066,246
Adjustments to reconcile net income to net cash provided by operating activities
Provision for credit losses	190,000	170,000	124,000
Depreciation and amortization of premises and equipment	106,996	99,019	96,496
Amortization of capitalized servicing rights	50,982	49,906	68,410
Amortization of core deposit and other intangible assets	42,613	26,424	33,824
Provision for deferred income taxes	174,013	396,596	92,848
Asset write-downs	21,036	9,029	6,593
Net gain on sales of assets	(63,222)	(67,759)	(6,859)
Net change in accrued interest receivable, payable	(12,282)	(46,338)	15,163
Net change in other accrued income and expense	60,263	(289,139)	(68,722)
Net change in loans originated for sale	(665,649)	323,330	(350,581)
Net change in trading account assets and liabilities	(36,453)	(8,327)	21,623
Net cash provided by operating activities	1,183,411	1,742,408	1,099,041
Cash flows from investing activities
Proceeds from sales of investment securities Available for sale	63,513	5,654,850	16
Proceeds from sales of investment securities Other	94,749	183,892	23,445
Proceeds from maturities of investment securities Available for sale	2,309,208	2,392,331	998,413
Proceeds from maturities of investment securities Held to maturity	609,080	662,959	468,999
Purchases of investment securities Available for sale	(3,562,711)	(3,614,324)	(5,347,145)
Purchases of investment securities Held to maturity	(214,791)	(29,431)	(21,283)
Purchases of investment securities Other	(1,808)	(99,317)	(53,606)
Net increase in loans and leases	(2,952,129)	(2,326,744)	(2,421,162)
Net (increase) decrease in interest-bearing deposits at banks	2,593,712	6,445,451	(4,819,729)
Capital expenditures, net	(107,693)	(81,936)	(73,161)
Net (increase) decrease in loan servicing advances	170,141	448,271	(484,689)
Acquisition of bank and bank holding company, net of cash acquired		(1,932,596)
Other, net	277,961	10,876	19,531
Net cash provided (used) by investing activities	(720,768)	7,714,282	(11,710,371)
Cash flows from financing activities
Net increase in deposits	3,554,673	504,393	6,466,697
Net decrease in short-term borrowings	(1,937,105)	(2,167,405)	(67,779)
Proceeds from long-term borrowings		1,500,000	4,345,478
Payments on long-term borrowings	(1,119,898)	(8,912,474)	(426,275)
Purchases of treasury stock	(641,334)
Dividends paid — common	(441,891)	(375,017)	(371,199)
Dividends paid — preferred	(81,270)	(81,270)	(70,234)
Redemption of Series D preferred stock	(500,000)
Proceeds from issuance of preferred stock	495,000		346,500
Other, net	161,691	69,766	88,565
Net cash provided (used) by financing activities	(510,134)	(9,462,007)	10,311,753
Net increase (decrease) in cash and cash equivalents	(47,491)	(5,317)	(299,577)
Cash and cash equivalents at beginning of year	1,368,040	1,373,357	1,672,934
Cash and cash equivalents at end of year	1,320,549	1,368,040	1,373,357
Supplemental disclosure of cash flow information
Interest received during the year	3,903,374	3,134,311	2,893,153
Interest paid during the year	498,951	400,329	257,553
Income taxes paid during the year	276,866	378,660	411,912
Supplemental schedule of noncash investing and financing activities
Real estate acquired in settlement of loans	124,033	67,753	43,821
Acquisition of bank and bank holding company
Common stock issued		3,110,581
Common stock awards converted		28,243
Fair value of Assets acquired (noncash)		36,567,632
Fair value of Liabilities assumed		31,496,212
Securitization of residential mortgage loans allocated to Available-for-sale investment securities	24,233	65,023	134,698
Securitization of residential mortgage loans allocated to Capitalized servicing rights	$ 248	$ 646	$ 1,760