Goodwill And Other Intangible Assets (Schedule Of Estimated Amortization Expense For Future Years) (Details) (USD $) In Thousands	6 Months Ended
Jun. 30, 2011
Goodwill And Other Intangible Assets
2011 remaining	$ 3,735
2012	6,684
2013	5,699
2014	4,713
2015	3,919
Thereafter	9,364
Total	$ 34,114

- Definition

The amount of amortization expense expected to be recognized for the remainder of the finite-lived intangible asset useful life after the fifth succeeding fiscal year.

+ Details

Name:	onb_FutureAmortizationExpenseAfterYearFive
Namespace Prefix:	onb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of amortization expense expected to be recognized during the remainder of the current fiscal year.

+ Details

Name:	onb_FutureAmortizationExpenseRemainderOfFiscalYear
Namespace Prefix:	onb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

GOODWILL AND OTHER INTANGIBLE ASSETS

+ Details

Name:	onb_GoodwillAndOtherIntangibleAssetsAbstract
Namespace Prefix:	onb
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate estimated amortization expense for each of the five succeeding fiscal years for intangible assets subject to amortization.

+ References