Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash Flows From Operating Activities:
Net income	$ 89,059	$ 83,193
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	(8,000)	0
Change in fair value of mortgage servicing rights	(2,658)	(7,127)
Unrealized (gains) losses from derivatives	9,334	(4,874)
Tax benefit on exercise of stock options	337	428
Change in bank-owned life insurance	(3,226)	(2,871)
Stock-based compensation	(751)	2,004
Depreciation and amortization	13,392	12,326
Net amortization of securities discounts and premiums	16,507	23,850
Net realized gains on financial instruments and other assets	(35,671)	(18,313)
Mortgage loans originated for resale	(956,315)	(747,435)
Proceeds from sale of mortgage loans held for resale	993,776	711,602
Capitalized mortgage servicing rights	(11,433)	(8,372)
Change in trading and fair value option securities	81,022	250,562
Change in receivables	(2,554)	(18,487)
Change in other assets	7,376	(1,720)
Change in accrued interest, taxes and expense	15,680	31,332
Change in other liabilities	33,543	10,787
Net cash provided by operating activities	239,418	316,885
Cash Flows From Investing Activities:
Proceeds from maturities or redemptions of investment securities	20,485	12,083
Proceeds from maturities or redemptions of available for sale securities	991,514	1,374,819
Purchases of investment securities	(110,957)	(146)
Purchases of available for sale securities	(1,529,068)	(2,346,849)
Proceeds from sales of available for sale securities	728,424	991,941
Change in amount receivable on unsettled securities transactions	20,364	(436,137)
Loans originated net of principal collected	221,433	(319,043)
Net proceeds from (payments on) derivative asset contracts	17,454	(116,683)
Proceeds from disposition of assets	26,870	38,761
Purchases of assets	(73,612)	(31,799)
Net cash provided by (used in) investing activities	312,907	(833,053)
Cash Flows From Financing Activities:
Net change in demand deposits, transaction deposits and savings accounts	(1,250,831)	(23,410)
Net change in time deposits	(67,938)	(215,883)
Net change in other borrowed funds	659,003	762,665
Net payments or proceeds on derivative liability contracts	(20,893)	110,679
Net change in derivative margin accounts	(57,241)	(15,630)
Change in amount due on unsettled security transactions	(138,469)	(348,205)
Issuance of common and treasury stock, net	9,542	7,101
Tax benefit on exercise of stock options	(337)	(428)
Repurchase of common stock	0	(18,432)
Dividends paid	(25,783)	(22,348)
Net cash provided by (used in) financing activities	(892,947)	236,109
Net decrease in cash and cash equivalents	(340,622)	(280,059)
Cash and cash equivalents at beginning of period	1,286,239	986,365
Cash and cash equivalents at end of period	945,617	706,306
Cash paid for interest	16,390	17,817
Cash paid for taxes	5,953	3,765
Net loans transferred to repossessed real estate and other assets	22,299	26,041
Residential mortgage loans guaranteed by U.S. government agencies that became eligible for repurchase during the period	28,192	23,184
Conveyance of other real estate owned guaranteed by U.S. government agencies	$ 11,155	$ 18,425