CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Retained Earnings	Cost of Common Stock in Treasury	Accumulated Other Comprehensive Income (Loss), Net
Balance at Dec. 31, 2011	$ 523,918	$ 346,535	$ 190,261	$ (31,389)	$ 18,511
Increase (Decrease) in Shareholders' Equity
Net income	37,287		37,287
Other comprehensive (loss) income	3,335				3,335
Issuance of 169,792 and 169,720 common shares under stock based compensation awards, including related tax effects for the nine months ended on September 30, 2013 and 2012, respectively	3,743		97	3,646
Cost of 89,867 and 104,471 shares of common stock acquired for treasury for the nine months ended on September 30, 2013 and 2012, respectively	(2,617)			(2,617)
Common stock dividend ($0.51 and $0.49 per share for the nine months ended on September 30, 2013 and 2012, respectively)	(11,998)		(11,998)
Balance at Sep. 30, 2012	553,668	346,535	215,647	(30,360)	21,846
Balance at Dec. 31, 2012	558,655	346,535	223,715	(31,134)	19,539
Increase (Decrease) in Shareholders' Equity
Net income	41,242		41,242
Other comprehensive (loss) income	(10,526)				(10,526)
Issuance of 169,792 and 169,720 common shares under stock based compensation awards, including related tax effects for the nine months ended on September 30, 2013 and 2012, respectively	3,650		(390)	4,040
Cost of 89,867 and 104,471 shares of common stock acquired for treasury for the nine months ended on September 30, 2013 and 2012, respectively	(2,268)			(2,268)
Common stock dividend ($0.51 and $0.49 per share for the nine months ended on September 30, 2013 and 2012, respectively)	(12,524)		(12,524)
Balance at Sep. 30, 2013	$ 578,229	$ 346,535	$ 252,043	$ (29,362)	$ 9,013