Financing Activities (Other Borrowings) (Details) (USD $) In Thousands, unless otherwise specified							9 Months Ended				9 Months Ended
	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2011 Minimum [Member] Junior Subordinated Debenture [Member]	Sep. 30, 2011 Minimum [Member] Federal Home Loan Bank Advances [Member]	Sep. 30, 2011 Maximum [Member] Junior Subordinated Debenture [Member]	Sep. 30, 2011 Maximum [Member] Federal Home Loan Bank Advances [Member]	Sep. 30, 2011 Securities Sold Under Agreements To Repurchase [Member]	Sep. 30, 2011 Junior Subordinated Debenture [Member]	Sep. 30, 2011 Subordinated Notes [Member]	Sep. 30, 2011 Subordinated Notes [Member] Old National Bancorp [Member]	Sep. 30, 2011 Federal Home Loan Bank Advances [Member]	Sep. 30, 2011 Subordinated Bank Notes [Member]	Sep. 30, 2011 Subordinated Bank Notes [Member] Old National Bank [Member]	Sep. 30, 2011 Old National Bancorp [Member]	Dec. 31, 2010 Old National Bancorp [Member]	Sep. 30, 2011 Old National Bank [Member]	Dec. 31, 2010 Old National Bank [Member]
Junior subordinated debenture (variable rates of 2.12% to 3.42% and fixed rates of 6.52% to 7.15%) maturing July 2033 to June 2037														$ 16,000	$ 8,000
Subordinated bank notes														13,000	0	150,000	150,000
ASC 815 fair value hedge and other basis adjustments														(2,844)	(36)	2,449	(2,056)
Securities sold under agreements to repurchase (variable rate 3.05%) maturing October 2014																50,000	50,000
Federal Home Loan Bank advances (fixed rates 1.24% to 8.34% and variable rate 2.53%) maturing June 2012 to January 2023																211,006	211,696
Capital lease obligation																4,273	4,307
Total other borrowings	$ 443,884	$ 421,911
Variable rates			2.12%		3.42%		3.05%				2.53%
Fixed rates			6.52%	1.24%	7.15%	8.34%				10.00%			6.75%
Maturity, Start date								July 2033			June 2012
Maturity, End date								June 2037			January 2023
Maturity date							Oct. 01, 2014		Jun. 01, 2019			Oct. 01, 2011