Consolidated Statements Of Changes In Shareholders' Equity (USD $) In Thousands, unless otherwise specified	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance at Dec. 31, 2010	$ 87,183	$ 748,873	$ 44,018	$ (1,269)	$ 878,805
Comprehensive income
Net income	0	0	16,433	0	16,433
Other comprehensive income
Change in unrealized gain (loss) on securities available for sale, net of reclassification and tax	0	0	0	4,641	4,641
Transferred securities, net of tax	0	0	0	(296)	(296)
Reclassification adjustment on cash flows hedges, net of tax	0	0	0	(147)	(147)
Net loss, settlement cost and amortization of net (gain) loss on defined benefit pension plans, net of tax	0	0	0	541	541
Total comprehensive income					21,172
Acquisition - Monroe Bancorp	7,575	82,495	0	0	90,070
Dividends - common stock	0	0	(6,630)	0	(6,630)
Common stock issued	5	51	0	0	56
Common stock repurchased	(32)	(299)	0	0	(331)
Stock based compensation expense	0	777	0	0	777
Stock activity under incentive comp plans	3	93	0	0	96
Balance at Mar. 31, 2011	94,734	831,990	53,821	3,470	984,015
Balance at Dec. 31, 2011	94,654	834,033	89,865	15,004	1,033,556
Comprehensive income
Net income	0	0	21,723	0	21,723
Other comprehensive income
Change in unrealized gain (loss) on securities available for sale, net of reclassification and tax	0	0	0	3,401	3,401
Transferred securities, net of tax	0	0	0	(138)	(138)
Reclassification adjustment on cash flows hedges, net of tax	0	0	0	(144)	(144)
Net loss, settlement cost and amortization of net (gain) loss on defined benefit pension plans, net of tax	0	0	0	604	604
Total comprehensive income					25,446
Dividends - common stock	0	0	(8,510)	0	(8,510)
Common stock issued	5	55	0	0	60
Common stock repurchased	(55)	(631)	0	0	(686)
Stock based compensation expense	0	499	0	0	499
Stock activity under incentive comp plans	70	20	(44)	0	46
Balance at Mar. 31, 2012	$ 94,674	$ 833,976	$ 103,034	$ 18,727	$ 1,050,411