Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash Flows From Operating Activities:
Net income	$ 229,898	$ 245,009
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Provision for credit losses	0	(16,500)
Change in fair value of mortgage servicing rights	5,624	(16,627)
Unrealized losses (gains) from derivative contracts	(7,853)	23,270
Tax effect from equity compensation, net	(8,176)	(301)
Change in bank-owned life insurance	(6,706)	(7,870)
Share-based compensation	11,815	4,537
Depreciation and amortization	40,833	40,820
Net amortization of securities discounts and premiums	43,078	47,468
Net realized gains on financial instruments and other assets	1,459	(7,917)
Net gain on mortgage loans held for sale	(43,764)	(79,045)
Mortgage loans originated for sale	(3,220,120)	(3,232,520)
Proceeds from sale of mortgage loans held for sale	3,091,285	3,364,095
Capitalized mortgage servicing rights	(39,183)	(39,157)
Change in trading and fair value option securities	(88,005)	177,953
Change in receivables	14,134	7,716
Change in other assets	36,931	58,311
Change in accrued interest, taxes and expense	(107,585)	5,398
Change in other liabilities	23,164	(5,676)
Net cash provided by (used in) operating activities	(23,171)	568,964
Cash Flows From Investing Activities:
Proceeds from maturities or redemptions of investment securities	54,666	113,570
Proceeds from maturities or redemptions of available for sale securities	1,326,128	2,197,656
Purchases of investment securities	(37,094)	(261,629)
Purchases of available for sale securities	(2,324,730)	(3,708,188)
Proceeds from sales of available for sale securities	1,884,061	2,140,531
Change in amount receivable on unsettled securities transactions	(77,707)	118,032
Loans originated net of principal collected	(845,432)	(27,426)
Net payments on derivative asset contracts	(102,302)	(67,707)
Acquisitions, net of cash acquired	(21,898)	0
Proceeds from disposition of assets	95,611	80,678
Purchases of assets	(193,597)	(120,539)
Net cash provided by (used in) investing activities	(242,294)	464,978
Cash Flows From Financing Activities:
Net change in demand deposits, transaction deposits and savings accounts	51,142	(1,439,433)
Net change in time deposits	(31,413)	(247,972)
Net change in other borrowed funds	1,773,313	817,105
Net proceeds on derivative liability contracts	114,985	61,764
Net change in derivative margin accounts	(45,724)	(105,226)
Change in amount due on unsettled security transactions	(37,614)	(183,194)
Issuance of common and treasury stock, net	(6,847)	14,945
Tax effect from equity compensation, net	8,176	301
Dividends paid	(82,207)	(77,486)
Net cash provided by (used in) financing activities	1,743,811	(1,159,196)
Net increase (decrease) in cash and cash equivalents	1,478,346	(125,254)
Cash and cash equivalents at beginning of period	1,087,213	1,286,239
Cash and cash equivalents at end of period	2,565,559	1,160,985
Supplemental Cash Flow Information [Abstract]
Cash paid for interest	47,264	51,689
Cash paid for taxes	61,627	104,589
Net loans and bank premises transferred to repossessed real estate and other assets	38,797	73,075
Residential mortgage loans guaranteed by U.S. government agencies that became eligible for repurchase during the period	100,430	88,618
Conveyance of other real estate owned guaranteed by U.S. government agencies	34,425	31,641
Issuance of shares in settlement of accrued executive compensation	$ 15,072	$ 0