Parent Company Financial Statements - Condensed Balance Sheets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets
Trading securities - at fair value	$ 4,982	$ 3,941
Other assets	115,776	106,639
Total assets	14,860,237	11,991,527
Liabilities and Shareholders' Equity
Other borrowings	218,939	218,256
Shareholders' equity	1,814,417	1,491,170	$ 1,465,764	$ 1,162,640
Total liabilities and shareholders' equity	14,860,237	11,991,527
Old National Bancorp [Member]
Assets
Deposits in affiliate bank	91,650	48,000
Trading securities - at fair value	4,982	3,941
Investment securities - available-for-sale	1,535	1,452
Investment in affiliates, Banking subsidiaries	1,862,244	1,551,924
Investment in affiliates, Non-banks	11,388	49,083
Other assets	90,872	84,598
Total assets	2,062,671	1,738,998
Liabilities and Shareholders' Equity
Other liabilities	33,407	33,608
Other borrowings	214,847	214,220
Shareholders' equity	1,814,417	1,491,170
Total liabilities and shareholders' equity	$ 2,062,671	$ 1,738,998