Quarterly Results Of Operations (Schedule Of Quarterly Results Of Operations) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Quarterly Results Of Operations [Abstract]
Total interest income	$ 111,799,000	$ 111,966,000	$ 97,127,000	$ 99,434,000	$ 97,716,000	$ 99,818,000	$ 101,217,000	$ 97,620,000	$ 420,327,000		$ 396,371,000		$ 270,387,000
Total interest expense	19,226,000	20,995,000	21,162,000	20,686,000	25,367,000	29,885,000	31,078,000	28,414,000	82,069,000		114,744,000		97,602,000
Net interest income	92,573,000	90,971,000	75,965,000	78,748,000	72,349,000	69,933,000	70,139,000	69,206,000	338,258,000		281,627,000		172,785,000
Provision for loan losses	4,278,000	6,127,000	9,990,000	5,471,000	11,224,000	5,128,000	12,899,000	13,201,000	25,867,000		42,451,000		45,370,000
Net interest income after provision for loan losses	88,295,000	84,844,000	65,975,000	73,277,000	61,125,000	64,805,000	57,240,000	56,005,000	312,391,000		239,176,000		127,415,000
Gain (loss) on sale of investments, net	793,000	1,206,000	1,428,000	47,000	93,000	4,176,000	60,000	922,000	3,475,000		5,251,000		6,736,000
Other noninterest income	34,662,000	35,914,000	29,560,000	28,248,000	37,959,000	32,605,000	30,644,000	27,431,000
Noninterest expense	99,726,000	99,566,000	92,706,000	81,732,000	81,102,000	80,371,000	75,775,000	67,000,000	373,731,000		304,249,000		223,260,000
Income (loss) before equity in undistributed earnings of subsidiaries	24,024,000	22,398,000	4,257,000	19,840,000	18,075,000	21,215,000	12,169,000	17,358,000	70,519,000		68,817,000		248,692,000
Income tax expense (benefit)	6,667,000	6,051,000	(929,000)	5,193,000	5,033,000	7,275,000	3,329,000	4,354,000	16,981,000		19,991,000		90,338,000
Net income	17,357,000	16,347,000	5,186,000	14,647,000	13,042,000	13,940,000	8,840,000	13,004,000	53,538,000		48,826,000		158,354,000
Preferred stock dividends													3,350,000
Income available to common shareholders	17,357,000	16,347,000	5,186,000	14,647,000	13,042,000	13,940,000	8,840,000	13,004,000	53,538,000		48,826,000		155,004,000
Earnings allocated to unvested restricted stock	(307,000)	(290,000)	(87,000)	(291,000)	(261,000)	(288,000)	(189,000)	(252,000)	967,000		971,000		3,910,000
Earnings available to common shareholders - Diluted	$ 17,050,000	$ 16,057,000	$ 5,099,000	$ 14,356,000	$ 12,781,000	$ 13,652,000	$ 8,651,000	$ 12,752,000	$ 52,571,000		$ 47,855,000		$ 151,094,000
Earnings per share - basic	$ 0.59	$ 0.55	$ 0.19	$ 0.54	$ 0.49	$ 0.52	$ 0.33	$ 0.60	$ 1.88	[1]	$ 1.90	[1]	$ 8.49	[1]
Earnings per share - diluted	$ 0.59	$ 0.54	$ 0.18	$ 0.54	$ 0.48	$ 0.52	$ 0.33	$ 0.59	$ 1.87		$ 1.88		$ 8.41

[1] Total earnings available to common shareholders include distributed earnings of $38,681,000, or $1.38 per weighted average share, and undistributed earnings of $13,869,000, or $0.50 per weighted average share for the year ended December 31, 2011. Total earnings available to common shareholders include distributed earnings of $35,772,000, or $1.42 per weighted average share, and undistributed earnings of $12,073,000, or $0.48 per weighted average share for the year ended December 31, 2010. Total earnings available to common shareholders include distributed earnings of $24,491,000, or $1.38 per weighted average share, and undistributed earnings of $126,296,000, or $7.11 per weighted average share for the year ended December 31, 2009.