CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Retained earnings	Accumulated other comprehensive income (loss)	Treasury stock
Beginning Balances at Dec. 31, 2012	$ 710,425	$ 579,293	$ 330,004	$ (18,677)	$ (180,195)
Beginning Balances (in shares) at Dec. 31, 2012		68,730,731			(10,684,496)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	44,564		44,564
Other comprehensive income (loss)	(10,617)			(10,617)
Cash dividends declared :
Common stock at $0.45 per share in 2014 and $0.79 per share in 2013	(45,575)		(45,575)
Purchase of common stock, in shares					(540,400)
Purchase of common stock	(8,339)				(8,339)
Excess tax benefit on share-based compensation	133	133
Exercise of stock options, net of shares purchased (in shares)					44,105
Exercise of stock options, net of shares purchased	(275)	(1,016)			741
Restricted stock awards, net of forfeitures (in shares)					152,504
Restricted stock awards, net of forfeitures	(1,326)	(4,030)			2,704
Share-based compensation expense	3,049	3,049
Ending Balances at Sep. 30, 2013	692,039	577,429	328,993	(29,294)	(185,089)
Ending Balances (in shares) at Sep. 30, 2013		68,730,731			(11,028,287)
Beginning Balances at Dec. 31, 2013	682,161	577,076	324,192	(31,281)	(187,826)
Beginning Balances (in shares) at Dec. 31, 2013		68,730,731			(11,197,685)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	46,401		46,401
Other comprehensive income (loss)	10,393			10,393
Cash dividends declared :
Common stock at $0.45 per share in 2014 and $0.79 per share in 2013	(26,475)		(26,475)
Purchase of common stock, in shares					(40,255)
Purchase of common stock	(697)				(697)
Common stock ssued in connection with business combinations, in shares					3,657,937
Common stock ssued in connection with business combinations	60,429	(946)			61,375
Excess tax benefit on share-based compensation	149	149
Exercise of stock options, net of shares purchased (in shares)					36,830
Exercise of stock options, net of shares purchased	(155)	(771)			616
Restricted stock awards, net of forfeitures (in shares)					180,915
Restricted stock awards, net of forfeitures	(1,186)	(4,191)			3,005
Share-based compensation expense	2,892	2,892
Ending Balances at Sep. 30, 2014	$ 773,912	$ 574,209	$ 344,118	$ (20,888)	$ (123,527)
Ending Balances (in shares) at Sep. 30, 2014		68,730,731			(7,362,258)