Investment Securities (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Proceeds from sales and calls of securities available for sale	$ 197,300,000	$ 308,700,000
Gains on sales of securities available for sale	7,600,000	3,000,000
Losses on sales of securities available for sale		1,000,000
Gains associated with trading securities	45,000	106,000
Securities - available-for-sale, at fair value	2,208,262,000	2,202,855,000	2,208,262,000	2,202,855,000	2,071,276,000
Amount of other-than-temporary impairment recognized in earnings	780,000	1,433,000	876,000	1,732,000
Trading securities that consist of mutual funds	2,918,000		2,918,000		2,816,000
Number of securities in security portfolio	1,081		1,081
Number of securities in unrealized loss position	53		53
Net unrealized losses	22,682,000		22,682,000		25,592,000
Number of securities recorded credit loss	5		5
Credit losses recorded	715,000
Non-agency Mortgage-Backed Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Securities - available-for-sale, at fair value	73,747,000		73,747,000		85,900,000
Number of securities with other-than-temporary impairment charges related to credit loss	5	3	5	3
Amount of other-than-temporary impairment recognized in earnings		500,000
Securities Held as Collateral, at Fair Value		84,100,000		84,100,000
Credit losses recorded		500,000
Pooled Trust Preferred Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Securities - available-for-sale, at fair value	8,460,000		8,460,000		7,327,000
Net unrealized losses	16,834,000		16,834,000		18,134,000
Number of securities recorded credit loss	8		8
Other-than-temporary impairment losses on pooled trust preferred security			161,000
Pooled trust preferred security fair value	475,000		475,000
Fair value of trust preferred securities	8,500,000		8,500,000
Pooled Trust Preferred Securities And Non-Agency Mortgage Backed Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Amount of other-than-temporary impairment recognized in earnings	876,000
FASB ASC 325-10 (EITF 99-20) [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Number of securities in unrealized loss position		7		7
Net unrealized losses	7,100,000	7,200,000	7,100,000	7,200,000
Number of securities recorded credit loss	6		6
Fair value of trust preferred securities	3,900,000		3,900,000
Other-than-temporary-impairment losses on securities	0
Trust Preferred Securities Which Are Not Subject To FASB ASC 325-10 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Net unrealized losses	9,700,000	10,400,000	9,700,000	10,400,000
Fair value of trust preferred securities	4,600,000	3,800,000	4,600,000	3,800,000
Other-than-temporary-impairment losses on securities	0
Investment Grade Range B To D [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Number of securities recorded credit loss	8		8
Investment Grade Rated B [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Number of securities recorded credit loss	1		1
Securities Held as Collateral, at Fair Value	13,700,000		13,700,000
Investment Grade Rated CCC [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Number of securities recorded credit loss	2		2
Securities Held as Collateral, at Fair Value	22,800,000		22,800,000
Investment Grade Rated CC [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Number of securities recorded credit loss	1		1
Securities Held as Collateral, at Fair Value	2,300,000		2,300,000
Investment Grade Rated C [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Number of securities recorded credit loss	1		1
Securities Held as Collateral, at Fair Value	16,100,000		16,100,000
Investment Grade Rated C [Member] | Pooled Trust Preferred Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Number of securities recorded credit loss	4		4
Investment Grade Rated D [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Number of securities recorded credit loss	3		3
Securities Held as Collateral, at Fair Value	9,200,000		9,200,000
Investment Grade Rated D [Member] | Pooled Trust Preferred Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Number of securities recorded credit loss	2		2
Non-Agency [Member] | Collateralized Mortgage Obligations [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Number of securities recorded credit loss		3		3
Remaining fair value of non-agency mortgage backed securities	64,000,000		64,000,000
Non-Agency [Member] | Collateralized Mortgage Obligations [Member] | Non-agency Mortgage-Backed Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Securities - available-for-sale, at fair value	73,700,000		73,700,000
Number of non-agency collateralized mortgage obligations	10		10
Net unrealized losses	3,100,000		3,100,000
Former Directors And Executives Of Monroe Bancorp [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Trading securities that consist of mutual funds	$ 2,900,000		$ 2,900,000		$ 2,800,000