Consolidated Statements of Changes in Shareholders' Equity (USD $) In Thousands	Total	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2011	$ 1,033,556	$ 94,654	$ 834,033	$ 89,865	$ 15,004
Net income	68,666			68,666
Other comprehensive income (loss)	19,276				19,276
Acquisition-Indiana Community Bancorp	88,497	6,626	81,871
Dividends-common stock	(25,551)			(25,551)
Common stock issued	187	16	171
Common stock repurchased	(831)	(66)	(765)
Stock based compensation expense	2,203		2,203
Stock activity under incentive comp plans	761	173	746	(158)
Balance at Sep. 30, 2012	1,186,764	101,403	918,259	132,822	34,280
Balance at Dec. 31, 2012	1,194,565	101,179	916,918	146,667	29,801
Net income	76,371			76,371
Other comprehensive income (loss)	(74,731)				(74,731)
Dividends-common stock	(30,275)			(30,275)
Common stock issued	214	17	197
Common stock repurchased	(11,124)	(839)	(10,285)
Stock based compensation expense	3,154		3,154
Stock activity under incentive comp plans	1,082	336	980	(234)
Balance at Sep. 30, 2013	$ 1,159,256	$ 100,693	$ 910,964	$ 192,529	$ (44,930)