Segment Information (Narrative) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 segment	Dec. 31, 2011	Dec. 31, 2010
Segment Information [Line Items]
Net interest income	$ 84,361,000	$ 74,150,000	$ 75,973,000	$ 74,273,000	$ 76,595,000	$ 72,592,000	$ 62,319,000	$ 61,367,000	$ 308,757,000	$ 272,873,000	$ 218,416,000
Noninterest expense	99,425,000	89,019,000	86,027,000	91,287,000	93,680,000	95,158,000	79,758,000	79,925,000	365,758,000	348,521,000	314,305,000
Income (loss) before income taxes	34,029,000	25,598,000	38,095,000	30,063,000	31,026,000	24,842,000	22,943,000	20,951,000	127,785,000	99,762,000	43,480,000
Decrease in total loans									16,200,000
Recapture of provision expense									5,500,000
Number of segments									2
Percentage of loan portfolio with higher loss factors										48.00%	58.00%
Percentage of loan portfolio with lower loss factors										21.00%	18.00%
Community Banking [Member]
Segment Information [Line Items]
Net interest income									286,934,000	302,285,000	252,519,000
Noninterest expense									261,117,000	287,097,000	236,642,000
Income (loss) before income taxes									142,378,000	129,446,000	73,108,000
Other Segment [Member]
Segment Information [Line Items]
Net interest income									48,804,000	12,981,000	(3,725,000)
Noninterest expense									93,151,000	60,677,000	63,860,000
Noninterest expense associated with credit impaired loans									19,300,000
Income (loss) before income taxes									3,058,000	221,000	(3,318,000)
Old National Bancorp [Member]
Segment Information [Line Items]
Income (loss) before income taxes									40,014,000	10,219,000	8,362,000
Integra Bank N.A [Member]
Segment Information [Line Items]
Income (loss) before income taxes										6,500,000
Integra Bank N.A [Member] | Community Banking [Member]
Segment Information [Line Items]
Net interest income									24,300,000	24,800,000
Indiana Community Bancorp [Member] | Community Banking [Member]
Segment Information [Line Items]
Net interest income									12,100,000	12,000,000
Indiana Community Bancorp [Member] | Other Segment [Member]
Segment Information [Line Items]
Net interest income									39,100,000
Monroe Bancorp [Member]
Segment Information [Line Items]
Noninterest expense									21,200,000
Income (loss) before income taxes										18,400,000
Monroe Bancorp [Member] | Community Banking [Member]
Segment Information [Line Items]
Net interest income									37,300,000
Noninterest expense										$ 25,900,000