Investment Securities (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended								12 Months Ended		3 Months Ended		3 Months Ended																															12 Months Ended
	Sep. 30, 2012	Dec. 31, 2012 security	Dec. 31, 2011 security	Dec. 31, 2010 security	Dec. 31, 2012 Non-agency Mortgage-Backed Securities [Member] security	Dec. 31, 2011 Non-agency Mortgage-Backed Securities [Member] security	Dec. 31, 2010 Non-agency Mortgage-Backed Securities [Member]	Dec. 31, 2012 Pooled Trust Preferred Securities Group 1 [Member] security	Dec. 31, 2011 Pooled Trust Preferred Securities Group 1 [Member]	Dec. 31, 2012 Pooled Trust Preferred Securities And Non-Agency Mortgage Backed Securities [Member]	Dec. 31, 2011 Pooled Trust Preferred Securities And Non-Agency Mortgage Backed Securities [Member]	Mar. 31, 2013 FASB ASC 325-10 (EITF 99-20) [Member]	Dec. 31, 2012 FASB ASC 325-10 (EITF 99-20) [Member] security	Mar. 31, 2013 Trust Preferred Securities Which Are Not Subject To FASB ASC 325-10 [Member]	Dec. 31, 2012 Trust Preferred Securities Which Are Not Subject To FASB ASC 325-10 [Member]	Dec. 31, 2011 Trust Preferred Securities Which Are Not Subject To FASB ASC 325-10 [Member]	Sep. 30, 2011 Trust Preferred Securities Which Are Not Subject To FASB ASC 325-10 [Member]	Dec. 31, 2011 Collateralized Mortgage Obligations [Member] Non-agency Mortgage-Backed Securities [Member] security	Dec. 31, 2012 Investment Grade AAA [Member] FASB ASC 325-10 (EITF 99-20) [Member]	Dec. 31, 2012 Investment Grade AA [Member] FASB ASC 325-10 (EITF 99-20) [Member]	Dec. 31, 2011 Investment Grade Range B To D [Member] Non-agency Mortgage-Backed Securities [Member] security	Dec. 31, 2012 Investment Grade Range CCC To D [Member] Non-agency Mortgage-Backed Securities [Member] security	Dec. 31, 2011 Investment Grade Rated B [Member] Non-agency Mortgage-Backed Securities [Member] security	Dec. 31, 2012 Investment Grade Rated CCC [Member] security	Dec. 31, 2012 Investment Grade Rated CCC [Member] Non-agency Mortgage-Backed Securities [Member]	Dec. 31, 2011 Investment Grade Rated CCC [Member] Non-agency Mortgage-Backed Securities [Member] security	Dec. 31, 2012 Investment Grade Rated CC [Member] Non-agency Mortgage-Backed Securities [Member] security	Dec. 31, 2011 Investment Grade Rated CC [Member] Non-agency Mortgage-Backed Securities [Member] security	Dec. 31, 2012 Investment Grade Rated CC [Member] Pooled Trust Preferred Securities Group 1 [Member] security	Dec. 31, 2011 Investment Grade Rated C [Member] security	Dec. 31, 2011 Investment Grade Rated C [Member] Non-agency Mortgage-Backed Securities [Member] security	Dec. 31, 2012 Investment Grade Rated C [Member] Pooled Trust Preferred Securities Group 1 [Member] security	Dec. 31, 2011 Investment Grade Rated C Or D [Member] FASB ASC 325-10 (EITF 99-20) [Member] security	Dec. 31, 2011 Investment Grade Rated D [Member] security	Dec. 31, 2012 Investment Grade Rated D [Member] Non-agency Mortgage-Backed Securities [Member]	Dec. 31, 2011 Investment Grade Rated D [Member] Non-agency Mortgage-Backed Securities [Member] security	Dec. 31, 2012 Investment Grade Rated D [Member] Pooled Trust Preferred Securities Group 1 [Member] security	Dec. 31, 2012 Old National Bancorp [Member]	Dec. 31, 2011 Old National Bancorp [Member]	Dec. 31, 2011 Non-Agency [Member] Collateralized Mortgage Obligations [Member] security	Dec. 31, 2012 Non-Agency [Member] Collateralized Mortgage Obligations [Member] Non-agency Mortgage-Backed Securities [Member] security	Sep. 30, 2012 Former Directors And Executives Of Monroe Bancorp [Member]	Dec. 31, 2011 Former Directors And Executives Of Monroe Bancorp [Member]	Dec. 31, 2012 Calls By Issuers [Member]	Dec. 31, 2011 Calls By Issuers [Member] Pooled Trust Preferred Securities And Non-Agency Mortgage Backed Securities [Member]	Dec. 31, 2010 Calls By Issuers [Member] Pooled Trust Preferred Securities And Non-Agency Mortgage Backed Securities [Member]	Dec. 31, 2012 Remaining Security [Member] Pooled Trust Preferred Securities Group 1 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Proceeds from sales and calls of securities available for sale		$ 227,600,000	$ 546,000,000	$ 481,500,000
Gains on sales of securities available for sale		14,900,000					21,700,000				9,600,000																																		900,000	800,000
Losses on sales of securities available for sale			1,100,000				4,600,000
Gains associated with trading securities		800,000				21,000				165,000
Securities - available-for-sale, at fair value		2,500,784,000	2,071,276,000		30,196,000			9,359,000	7,327,000																													1,826,000	1,204,000		30,200,000			148,600,000		836,100,000
Number of securities with other-than-temporary impairment charges related to credit loss				10	6
Amount of other-than-temporary impairment recognized in earnings		1,414,000	3,252,000	5,060,000		1,400,000	3,900,000
Trading securities that consist of mutual funds		3,097,000				158,000,000																																				3,100,000	2,800,000
Number of trust preferred securities				3	2	1
Securities pledged to secure public and other funds, carrying value		834,000,000	835,000,000
Investment securities issued by states and political subdivisions, market value		273,800,000	268,400,000
State and political subdivision investment, equity percentage		22.90%	26.00%
Held-to-maturity securities transferred to available-for-sale		46,100,000
Held-to-maturity securities, unrealized gain reclassified out of other comprehensive income	1,000,000
Number of securities in security portfolio		1,297	8		6			6													9		1			2		4			1		6
Number of securities in unrealized loss position		103
Number of non-agency collateralized mortgage obligations																		13																							7
Net unrealized losses		19,880,000	25,592,000			4,500,000		15,525,000	18,134,000						8,800,000	11,100,000			6,700,000														7,000,000								800,000
Number of securities rated													4									6		1			1		1	4		2		2		1	1			3
Securities Held as Collateral, at Fair Value						85,900,000										73,200,000							13,800,000		5,000,000	24,200,000	12,600,000	14,000,000			17,600,000				9,000,000	3,600,000									362,400,000
Remaining fair value of non-agency mortgage backed securities					27,100,000
Credit losses recorded					900,000	500,000
Other-than-temporary impairment losses on pooled trust preferred security			900,000					476,000
Unrealized holding gain		9,400,000
Pooled trust preferred security fair value			9,000					9,400,000	7,300,000						5,500,000		3,100,000			3,900,000													4,200,000														501,000
Other-than-temporary-impairment gains on securities					$ 1,400,000							$ 0		$ 0