CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Retained Earnings	Cost of Common Stock in Treasury	Accumulated Other Comprehensive Income (Loss), Net
Balance at Dec. 31, 2015	$ 644,053	$ 436,538	$ 251,812	$ (50,852)	$ 6,555
Increase (Decrease) in Shareholders' Equity
Net income	13,818		13,818
Other comprehensive income (loss)	2,744				2,744
Issuance of 48,765 and 91,340 common shares under stock based compensation awards, including related tax effects for the three months ended on March 31, 2017 and 2016, respectively	2,069		(111)	2,180
Cost of 900 and 269,667 shares of common stock acquired for treasury for the three months ended on March 31, 2017 and 2016, respectively	(8,005)			(8,005)
Common stock dividend ($0.18 and $0.18 per share for the three months ended on March 31, 2017 and 2016, respectively)	(4,706)		(4,706)
Balance at Mar. 31, 2016	649,973	436,538	260,813	(56,677)	9,299
Balance at Dec. 31, 2016	672,650	436,538	290,824	(56,056)	1,344
Cumulative-effect adjustment at Dec. 31, 2016	(65)		(65)
Balance, adjusted at Dec. 31, 2016	672,585	436,538	290,759	(56,056)	1,344
Increase (Decrease) in Shareholders' Equity
Net income	16,206		16,206
Other comprehensive income (loss)	(17)				(17)
Issuance of 48,765 and 91,340 common shares under stock based compensation awards, including related tax effects for the three months ended on March 31, 2017 and 2016, respectively	1,878		721	1,157
Cost of 900 and 269,667 shares of common stock acquired for treasury for the three months ended on March 31, 2017 and 2016, respectively	(41)			(41)
Common stock dividend ($0.18 and $0.18 per share for the three months ended on March 31, 2017 and 2016, respectively)	(4,677)		(4,677)
Balance at Mar. 31, 2017	$ 685,934	$ 436,538	$ 303,009	$ (54,940)	$ 1,327