Consolidated Statements Of Changes In Shareholders' Equity (USD $) In Thousands	Preferred Stock [Member]	Common Stock [Member]	Surplus [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance at Dec. 31, 2009	$ 284,824	$ 27,079	$ 589,939	$ (122,733)	$ 366,152	$ (6,622)	$ 1,138,639
Comprehensive income:
Net income					29,027		29,027
Other comprehensive income, net of tax:
Unrealized gains on securities, net of reclassification adjustment						12,040	12,040
Unrealized gains (losses) on derivative instruments						(296)	(296)
Comprehensive income							40,771
Cash dividends declared on common stock					(2,191)		(2,191)
Dividends on preferred stock					(8,251)		(8,251)
Accretion on preferred stock	1,636				(1,636)
Common stock repurchases				(102)			(102)
Stock-based compensation			2,505				2,505
Cumulative effect of change in accounting for loan securitizations					(1,132)	(156)	(1,288)
Common stock issued for:
New issuance, net of costs		3,795	83,791	122,831			210,417
Exercise of stock options and warrants		108	2,198				2,306
Restricted stock awards		41	(91)				(50)
Employee stock purchase plan		13	482				495
Director compensation plan		48	1,437				1,485
Other comprehensive income (loss)
Unrealized gains on available-for-sale securities arising during the period, net							20,023
Unrealized gains (losses) on derivative instruments arising during the period, net							(482)
Less: Reclassification adjustment for gains included in net income, net							438
Less: Income tax expense							7,359
Other comprehensive income							11,744
Balance at Jun. 30, 2010	286,460	31,084	680,261	(4)	381,969	4,966	1,384,736
Balance at Dec. 31, 2010	49,640	34,864	965,203		392,354	(5,512)	1,436,549
Comprehensive income:
Net income					28,152		28,152
Other comprehensive income, net of tax:
Unrealized gains on securities, net of reclassification adjustment						7,690	7,690
Unrealized gains (losses) on derivative instruments						1,954	1,954
Comprehensive income							37,796
Cash dividends declared on common stock					(3,145)		(3,145)
Dividends on preferred stock					(2,000)		(2,000)
Accretion on preferred stock	64				(64)
Common stock repurchases				(50)			(50)
Stock-based compensation			2,034				2,034
Common stock issued for:
Exercise of stock options and warrants		45	567				612
Restricted stock awards		25	(28)				(3)
Employee stock purchase plan		29	868				897
Director compensation plan		25	671				696
Other comprehensive income (loss)
Unrealized gains on available-for-sale securities arising during the period, net							14,013
Unrealized gains (losses) on derivative instruments arising during the period, net							3,203
Less: Reclassification adjustment for gains included in net income, net							1,258
Less: Income tax expense							6,314
Other comprehensive income							9,644
Balance at Jun. 30, 2011	$ 49,704	$ 34,988	$ 969,315	$ (50)	$ 415,297	$ 4,132	$ 1,473,386