Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Operating activities:
Net income	$ 56,237	$ 66,145
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for probable loan losses	11,392	2,163
Specific reserve, other real estate owned	741	7,710
Accretion of time deposit discounts		(7)
Depreciation of bank premises and equipment	13,717	16,258
Gain on sale of bank premises and equipment	(319)	(332)
Gain on sale of other real estate owned	(395)	(254)
Accretion of investment securities discounts	(1,521)	(870)
Amortization of investment securities premiums	13,339	10,223
Investment securities transactions, net	(2,592)	(2,861)
Impairment charges on available-for-sale investment securities	408	415
Amortization of junior subordinated debenture discounts		9
Amortization of identified intangible assets	2,300	2,626
Stock based compensation expense	253	195
Earnings from affiliates and other investments	(7,348)	(8,980)
Deferred tax expense (benefit)	2,869	(2,283)
Decrease in accrued interest receivable	712	1,691
Net (increase) decrease in other assets	(123)	34,476
Net increase in other liabilities	5,138	2,942
Net cash provided by operating activities	94,808	129,266
Investing activities:
Proceeds from maturities of held-to-maturity securities	1,100	500
Proceeds from sales and calls of available for sale securities	72,383	774,856
Purchases of available for sale securities	(792,642)	(1,331,496)
Principal collected on mortgage-backed securities	643,667	497,445
Net decrease in loans	94,229	62,252
Purchases of other investments	(1,860)	(2,173)
Distributions received on other investments	23,006	13,556
Purchases of bank premises and equipment	(17,282)	(9,018)
Proceeds from sales of other real estate owned	15,066	7,341
Proceeds from sale of bank premises and equipment	2,501	1,109
Net cash provided by investing activities	40,168	14,372
Financing activities:
Net increase in non-interest bearing demand deposits	108,245	107,280
Net (decrease) increase in savings and interest bearing demand deposits	(2,828)	149,421
Net increase (decrease) in time deposits	108,114	(69,367)
Net decrease in securities sold under repurchase agreements	(18,631)	(9,681)
Net decrease in other borrowed funds	(352,066)	(270,879)
Repayment of long-term debt		(5,200)
Purchase of treasury stock	(971)	(2,951)
Proceeds from stock transactions	33	110
Payments of dividends on common stock	(13,450)	(12,863)
Payments of dividends on preferred stock	(5,400)	(5,400)
Net cash used in financing activities	(176,954)	(119,530)
(Decrease) increase in cash and cash equivalents	(41,978)	24,108
Cash and cash equivalents at beginning of period	261,885	197,814
Cash and cash equivalents at end of period	219,907	221,922
Supplemental cash flow information:
Interest paid	42,268	52,494
Income taxes paid	14,719	42,773
Non-cash investing and financing activities:
Accrued dividends, preferred shares	1,350	1,350
Net transfer from loans to other real estate owned	57,605	42,383
Purchases of available-for-sale securities not yet settled	2,427
Accrued partial redemption of trust preferred securities, IB Capital Trust I		$ 5,200