Parent Company Financial Statements (Statement Of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net income	$ 91,675	$ 72,460	$ 38,214
Depreciation	11,306	9,674	8,990
Net premium (discount) amortization on investment securitie	(13,816)	(12,135)	(7,590)
Decrease in other assets	15,452	14,345	14,582
(Decrease) increase in other liabilities	(14,630)	12,276	(17,995)
Total adjustments	22,615	70,626	58,296
Net cash flows provided by operating activities	114,290	143,086	96,510
Purchases of investment securities	(1,031,124)	(550,934)	(1,106,040)
Proceeds from sales of investment securities available-for-sale	227,566	545,995	481,471
Purchases of premises and equipment and other assets	(18,712)	(11,486)	(7,460)
Net cash flows provided by (used in) investing activities	(11,692)	1,005,973	436,568
Payments related to retirement of debt	(67,949)	(211,228)	(279,649)
Cash dividends paid on common stock	(34,657)	(26,513)	(24,361)
Common stock repurchased	(3,990)	(1,526)	(705)
Common stock reissued under stock option, restricted stock and stock purchase plans	717	140	12
Common stock issued	254	222	197
Net cash flows used in financing activities	(61,410)	(1,177,739)	(778,802)
Net increase (decrease) in cash and cash equivalents	41,188	(28,680)	(245,724)
Cash and cash equivalents at beginning of period	222,872	251,552	497,276
Cash and cash equivalents at end of period	264,060	222,872	251,552
Old National Bancorp [Member]
Net income	91,675	72,460	38,214
Depreciation	15	31	49
Net securities (gains) losses	(134)	(20)	0
Stock compensation expense	3,317	3,436	2,369
Decrease in other assets	9,056	(4,927)	13,064
(Decrease) increase in other liabilities	(496)	3,628	(3,414)
Equity in undistributed earnings of affiliates	(45,752)	(58,422)	(22,019)
Total adjustments	(33,994)	(56,274)	(9,951)
Net cash flows provided by operating activities	57,681	16,186	28,263
Cash and cash equivalents of acquisitions	1	447	0
Transfer subsidiary from parent to bank subsidiary	0	0	791
Purchases of investment securities	(147)	0	(500)
Proceeds from sales of investment securities available-for-sale	0	1,081	0
Net payments from (advances to) affiliates	0	18,886	150,852
Purchases of premises and equipment and other assets	(173)	0	(7)
Net cash flows provided by (used in) investing activities	(319)	20,414	151,136
Payments related to retirement of debt	(16,000)	0	(150,000)
Cash dividends paid on common stock	(34,657)	(26,513)	(24,361)
Common stock repurchased	(3,990)	(1,526)	(705)
Common stock reissued under stock option, restricted stock and stock purchase plans	717	140	12
Common stock issued	254	222	197
Net cash flows used in financing activities	(53,676)	(27,677)	(174,857)
Net increase (decrease) in cash and cash equivalents	3,686	8,923	4,542
Cash and cash equivalents at beginning of period	35,576	26,653	22,111
Cash and cash equivalents at end of period	$ 39,262	$ 35,576	$ 26,653