Fair Value Part 3 (Details) (USD $)				12 Months Ended
	Dec. 31, 2011	Apr. 15, 2011	Dec. 31, 2010	Dec. 31, 2011 Estimate of Fair Value, Fair Value Disclosure [Member]	Dec. 31, 2010 Estimate of Fair Value, Fair Value Disclosure [Member]	Dec. 31, 2011 Fair Value, Measurements, Recurring [Member] Carrying (Reported) Amount, Fair Value Disclosure [Member]	Dec. 31, 2010 Fair Value, Measurements, Recurring [Member] Carrying (Reported) Amount, Fair Value Disclosure [Member]	Dec. 31, 2011 Fair Value, Measurements, Recurring [Member] Estimate of Fair Value, Fair Value Disclosure [Member]	Dec. 31, 2010 Fair Value, Measurements, Recurring [Member] Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Values, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and short-term investments						$ 211,883,000	$ 173,317,000	$ 211,883,000	$ 173,317,000
Securities available for sale	2,468,993,000		2,177,249,000			2,468,993,000	2,177,249,000	2,468,993,000	2,177,249,000
Securities held to maturity	57,705,000		140,847,000			57,705,000	140,847,000	62,515,000	145,143,000
Loans held for sale	216,553,000		153,044,000			216,553,000	153,044,000	216,553,000	153,044,000
Net LHFI, excluding covered loans	5,767,966,000		5,966,732,000			5,767,966,000	5,966,732,000	5,848,791,000	6,030,219,000
Covered loans	76,302,000		0			76,302,000	0	76,302,000	0
FDIC indemnification asset	28,348,000	33,333,000	0			28,348,000	0	28,348,000	0
Other assets - derivatives	3,521,000		(2,247,000)			3,521,000	(2,247,000)	3,521,000	(2,247,000)
Deposits	7,566,363,000		7,044,567,000			7,566,363,000	7,044,567,000	7,575,064,000	7,054,611,000
Short-term liabilities						692,128,000	1,125,481,000	692,128,000	1,125,481,000
Long-term FHLB advances						0	0	0	0
Subordinated notes	49,839,000		49,806,000			49,839,000	49,806,000	51,438,000	48,750,000
Junior subordinated debt securities	61,856,000		61,856,000			61,856,000	61,856,000	35,876,000	30,928,000
Other liabilities - derivatives	4,680,000		(1,581,000)			4,680,000	(1,581,000)	4,680,000	(1,581,000)
Outstanding balances in impaired loans	68,900,000		97,600,000	68,900,000	97,600,000
Nonfinancial Assets and Liabilities [Abstract]
Foreclosed assets measured at fair value				56,900,000	61,800,000
Allowance for possible loan losses, Charge-offs				6,700,000	5,500,000
Foreclosed assets re-measured after initial recognition				66,700,000	54,200,000
Write-downs Of Allowance For Foreclosed Assets After Initial Recognition				$ 13,900,000	$ 17,100,000
Estimated fair value of financial instruments with immediate and shorter-term maturities maximum (in days)				90 days or less
Family residential properties, bedrooms (minimum)				1
Family residential properties (maximum)				4