Consolidated Statements of Cash Flows (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Operating activities:
Net income	$ 87,408,000	$ 82,115,000
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for probable loan losses	17,561,000	16,741,000
Specific reserve, other real estate owned	478,000	2,032,000
Depreciation of bank premises and equipment	19,677,000	20,335,000
Gain on sale of bank premises and equipment	(626,000)	(734,000)
Gain on sale of other real estate owned	(201,000)	(239,000)
Accretion of investment securities discounts	(2,844,000)	(2,346,000)
Amortization of investment securities premiums	35,666,000	20,290,000
Investment securities transactions, net	(9,601,000)	(35,527,000)
Impairment charges on available-for-sale investment securities	1,300,000	647,000
Amortization of identified intangible assets	3,451,000	3,463,000
Stock based compensation expense	322,000	366,000
Earnings from affiliates and other investments	(16,085,000)	(8,836,000)
Deferred tax (benefit) expense	(2,325,000)	2,267,000
Decrease in accrued interest receivable	2,051,000	1,516,000
Net decrease (increase) in other assets	16,624,000	(271,000)
Net increase in other liabilities	7,535,000	16,793,000
Net cash provided by operating activities	160,391,000	118,612,000
Investing activities:
Proceeds from maturities of held-to-maturity securities		1,125,000
Proceeds from sales and calls of available for sale securities	178,124,000	1,279,963,000
Purchases of available for sale securities	(1,274,574,000)	(2,383,774,000)
Principal collected on mortgage-backed securities	1,025,015,000	955,550,000
Net (increase) decrease in loans	(285,453,000)	86,501,000
Purchases of other investments	(1,637,000)	(2,956,000)
Distributions received on other investments	4,159,000	8,845,000
Purchases of bank premises and equipment	(30,792,000)	(23,650,000)
Proceeds from sales of other real estate owned	19,303,000	25,643,000
Proceeds from sale of bank premises and equipment	653,000	3,795,000
Net cash used in investing activities	(365,202,000)	(48,958,000)
Financing activities:
Net increase in non-interest bearing demand deposits	185,882,000	182,477,000
Net decrease in savings and interest bearing demand deposits	(108,029,000)	(22,938,000)
Net decrease in time deposits	(252,260,000)	(114,460,000)
Net decrease in securities sold under repurchase agreements	(128,542,000)	(175,017,000)
Net increase in other borrowed funds	540,466,000	120,900,000
Purchase of treasury stock		(1,092,000)
Redemption of senior preferred shares		(40,000,000)
Proceeds from stock transactions	146,000	43,000
Payments of dividends on common stock	(13,438,000)	(13,450,000)
Payments of dividends on preferred stock		(7,911,000)
Net cash provided by (used in) financing activities	224,225,000	(71,448,000)
Increase (decrease) in cash and cash equivalents	19,414,000	(1,794,000)
Cash and cash equivalents at beginning of period	283,100,000	261,885,000
Cash and cash equivalents at end of period	302,514,000	260,091,000
Supplemental cash flow information:
Interest paid	43,405,000	60,651,000
Income taxes paid	45,480,000	22,271,000
Non-cash investing and financing activities:
Accrued dividends, preferred shares		1,100,000
Dividends declared, not yet paid on common stock	15,456,000	13,445,000
Net transfer from loans to other real estate owned	(371,000)	55,694,000
Purchases of available-for-sale securities not yet settled		$ 442,240,000