Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash Flows From Operating Activities:
Net income	$ 318,931	$ 354,124	$ 289,824
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	(27,900)	(22,000)	(6,050)
Change in fair value of mortgage servicing rights	(22,720)	9,210	40,447
Net unrealized losses (gains) from derivatives	16,256	(984)	(9,651)
Tax benefit on exercise of stock options	(2,210)	(120)	(659)
Change in bank-owned life insurance	(10,155)	(11,089)	(11,280)
Stock-based compensation	7,069	8,030	9,396
Depreciation and amortization	53,261	54,935	49,967
Net amortization of securities discounts and premiums	62,274	87,769	112,227
Net realized losses (gains) on financial instruments and other assets	(12,586)	(15,097)	53,829
Net gain on mortgage loans held for sale	(84,403)	(120,599)	(57,418)
Mortgage loans originated for resale	(4,081,390)	(3,708,350)	(2,293,436)
Proceeds from sale of mortgage loans held for resale	4,254,151	3,731,830	2,369,895
Capitalized mortgage servicing rights	(49,431)	(42,191)	(26,251)
Change in trading and fair value option securities	237,581	226,144	(247,386)
Change in receivables	(3,122)	9,244	24,236
Change in other assets	76,257	10,999	16,469
Change in accrued interest, taxes and expense	18,192	23,424	63,827
Change in other liabilities	(13,735)	(3,729)	(50,198)
Net cash provided by operating activities	736,320	591,550	327,788
Cash Flows From Investing Activities:
Proceeds from maturities or redemptions of investment securities	143,445	111,511	68,020
Proceeds from maturities or redemptions of available for sale securities	2,650,045	4,456,363	3,650,900
Purchases of investment securities	(326,815)	(172,327)	(37,085)
Purchases of available for sale securities	(4,287,146)	(7,334,843)	(7,504,261)
Proceeds from sales of available for sale securities	2,436,093	1,744,662	2,725,760
Change in amount receivable on unsettled securities transactions	193,878	(135,901)	59,908
Loans originated net of principal collected	(441,474)	(1,077,075)	(598,499)
Net proceeds from (payments on) derivative asset contracts	59,390	(13,273)	4,994
Acquisitions, net of cash acquired	(7,500)	(23,615)	0
Proceeds from disposition of assets	229,405	170,907	122,314
Purchases of assets	(212,292)	(94,756)	(56,195)
Net cash provided by (used in) investing activities	437,029	(2,368,347)	(1,564,144)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Net change in demand deposits, transaction deposits and savings accounts	(637,734)	2,830,470	1,710,705
Net change in time deposits	(271,999)	(413,990)	(127,026)
Net change in other borrowings	(111,905)	210,607	(949,051)
Repayment of subordinated debt	0	(53,705)	0
Net payments or proceeds on derivaive liability contracts	(64,724)	(7,560)	15,674
Net change in derivative margin accounts	51,646	39,237	(102,262)
Change in amount due on unsettled security transactions	(251,713)	(355,918)	492,946
Issuance of common and treasury stock, net	16,566	14,650	14,541
Sale of non-controlling interest	0	300	0
Tax benefit on exercise of stock options	2,210	120	659
Repurchase of common stock	0	(20,558)	(26,446)
Dividends paid	(104,722)	(166,982)	(76,423)
Net cash provided by (used in) financing activities	(1,372,375)	2,076,671	953,317
Net increase (decrease) in cash and cash equivalents	(199,026)	299,874	(283,039)
Cash and cash equivalents at beginning of period	1,286,239	986,365	1,269,404
Cash and cash equivalents at end of period	1,087,213	1,286,239	986,365
Cash paid for interest	69,830	90,137	122,166
Cash paid for taxes	132,176	158,703	156,465
Net loans transferred to real estate and other repossessed assets	86,868	133,502	87,476
Residential mortgage loans guaranteed by U.S. government agencies that became elgible fo repurchase during the year	127,572	121,432	154,134
Conveyance of other real estate owned guaranteed by U.S. government agencies	$ 43,901	$ 89,223	$ 14,501