Condensed Consolidated Statements Of Cash Flows (USD $)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 73,933,000	$ 53,114,000
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of investment premiums, net	33,023,000	24,582,000
Gain on sale of investment securities, net	(1,199,000)	(7,491,000)
Other-than-temporary impairment on investment securities held to maturity		72,000
Loss on sale of non-covered other real estate owned	481,000	1,449,000
Gain on sale of covered other real estate owned	(1,031,000)	(1,469,000)
Valuation adjustment on non-covered other real estate owned	5,763,000	7,518,000
Valuation adjustment on covered other real estate owned	4,115,000	7,247,000
Provision for non-covered loan and lease losses	16,883,000	39,578,000
Provision for covered loan and lease losses	4,302,000	15,443,000
Change in FDIC indemnification asset	10,644,000	1,035,000
Depreciation, amortization and accretion	11,848,000	9,454,000
Increase in mortgage servicing rights	(11,923,000)	(4,100,000)
Change in mortgage servicing rights carried at fair value	5,618,000	1,942,000
Change in junior subordinated debentures carried at fair value	1,633,000	1,636,000
Stock-based compensation	2,981,000	2,930,000
Net (increase) decrease in trading account assets	(744,000)	543,000
Gain on sale of loans	(36,378,000)	(6,585,000)
Origination of loans held for sale	(1,359,520,000)	(518,915,000)
Proceeds from sales of loans held for sale	1,268,707,000	506,831,000
Excess tax benefits from the exercise of stock options	(51,000)	(4,000)
Change in other assets and liabilities:
Net decrease in other assets	(6,323,000)	(4,066,000)
Net increase in other liabilities	22,493,000	11,905,000
Net cash provided by operating activities	45,255,000	142,649,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of investment securities available for sale	(784,797,000)	(822,898,000)
Purchases of investment securities held to maturity	(931,000)	(1,573,000)
Proceeds from investment securities available for sale	1,018,791,000	665,131,000
Proceeds from investment securities held to maturity	511,000	1,486,000
Redemption of restricted equity securities	1,216,000	1,766,000
Net non-covered loan and lease originations	(391,733,000)	(249,199,000)
Net covered loan and lease paydowns	85,510,000	75,791,000
Proceeds from sales of non-covered loans	13,496,000	9,262,000
Proceeds from disposals of furniture and equipment	1,700,000	199,000
Purchases of premises and equipment	(17,155,000)	(23,137,000)
Net proceeds from FDIC indemnification asset	26,615,000	57,885,000
Proceeds from sales of non-covered other real estate owned	18,834,000	25,691,000
Proceeds from sales of covered other real estate owned	11,523,000	12,550,000
Net cash used by investing activities	(16,420,000)	(247,046,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net decrease in deposit liabilities	(136,519,000)	(28,606,000)
Net increase in securities sold under agreements to repurchase	36,446,000	72,602,000
Repayment of term debt		(5,000,000)
Dividends paid on common stock	(25,919,000)	(17,260,000)
Excess tax benefits from stock based compensation	51,000	4,000
Proceeds from stock options exercised	324,000	310,000
Retirement of common stock	(5,378,000)	(2,061,000)
Net cash (used) provided by financing activities	(130,995,000)	19,989,000
Net decrease in cash and cash equivalents	(102,160,000)	(84,408,000)
Cash and cash equivalents, beginning of period	598,766,000	1,004,125,000
Cash and cash equivalents, end of period	496,606,000	919,717,000
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Interest	40,653,000	62,680,000
Income taxes	31,825,000	24,133,000
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Change in unrealized gains on investment securities available for sale, net of taxes	(2,019,000)	18,133,000
Change in unrealized losses on investment securities held to maturity related to factors other than credit, net of taxes	114,000	52,000
Cash dividend declared on common stock and payable after period-end	10,140,000	8,056,000
Transfer of non-covered loans to non-covered other real estate owned	10,167,000	36,654,000
Transfer of covered loans to covered other real estate owned	3,227,000	11,924,000
Transfer of covered loans to non-covered loans	14,367,000	10,610,000
Transfer from FDIC indemnification asset to due from FDIC and other	19,939,000	39,000,000
Receivable from sales of covered other real estate owned		$ 420,000