Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Cash Flows From Operating Activities:
Net income	$ 153,772	$ 168,947
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Provision for credit losses	0	(8,000)
Change in fair value of mortgage servicing rights	10,905	(16,973)
Unrealized losses (gains) from derivative contracts	(1,371)	6,137
Tax effect from equity compensation, net	(7,333)	(178)
Change in bank-owned life insurance	(4,380)	(5,462)
Stock-based compensation	6,710	1,357
Depreciation and amortization	26,090	27,634
Net amortization of securities discounts and premiums	28,279	32,867
Net realized gains on financial instruments and other assets	(2,021)	(9,784)
Net gain on mortgage loans held for sale	(29,733)	(47,998)
Mortgage loans originated for sale	(1,818,145)	(2,152,353)
Proceeds from sale of mortgage loans held for resale	1,721,995	2,201,324
Capitalized mortgage servicing rights	(21,816)	(25,932)
Change in trading and fair value option securities	(28,867)	100,889
Change in receivables	4,608	(23,890)
Change in other assets	45,929	38,648
Change in accrued interest, taxes and expense	(124,579)	(1,001)
Change in other liabilities	23,629	(13,407)
Net cash provided by (used in) operating activities	(16,328)	272,825
Cash Flows From Investing Activities:
Proceeds from maturities or redemptions of investment securities	34,074	99,020
Proceeds from maturities or redemptions of available for sale securities	805,216	1,689,165
Purchases of investment securities	(9,593)	(217,160)
Purchases of available for sale securities	(1,597,081)	(3,173,504)
Proceeds from sales of available for sale securities	1,340,190	1,837,970
Change in amount receivable on unsettled securities transactions	3,149	28,905
Loans originated net of principal collected	(604,979)	(130,381)
Net payments on derivative asset contracts	(117,280)	(229,888)
Acquisitions, net of cash acquired	(21,898)	0
Proceeds from disposition of assets	52,871	53,191
Purchases of assets	(56,778)	(115,250)
Net cash used in investing activities	(172,109)	(157,932)
Cash Flows From Financing Activities:
Net change in demand deposits, transaction deposits and savings accounts	382,704	(1,482,810)
Net change in time deposits	(80,167)	(200,020)
Net change in other borrowed funds	223,824	1,311,756
Net proceeds on derivative liability contracts	119,269	220,024
Net change in derivative margin accounts	(218,491)	114,958
Change in amount due on unsettled security transactions	78,797	(248,084)
Issuance of common and treasury stock, net	(9,376)	12,879
Tax effect from equity compensation, net	7,333	178
Dividends paid	(54,795)	(51,626)
Net cash provided by (used in) financing activities	449,098	(322,745)
Net increase (decrease) in cash and cash equivalents	260,661	(207,852)
Cash and cash equivalents at beginning of period	1,087,213	1,286,239
Cash and cash equivalents at end of period	1,347,874	1,078,387
Supplemental Cash Flow Information [Abstract]
Cash paid for interest	32,535	36,615
Cash paid for taxes	50,187	73,527
Net loans and bank premises transferred to repossessed real estate and other assets	38,797	52,967
Residential mortgage loans guaranteed by U.S. government agencies that became eligible for repurchase during the period	63,898	55,938
Conveyance of other real estate owned guaranteed by U.S. government agencies	18,312	22,527
Issuance of shares in settlement of accrued executive compensation	$ 15,072	$ 0