CONDENSED CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY - 9 months ended Sep. 30, 2016 - USD ($) $ in Thousands	Total	Capital Stock/Capital Shares	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Balance, Beginning of Period at Dec. 31, 2015	$ 584,582	$ 17,957	$ 112,017	$ 543,066	$ (88,458)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	36,370			36,370
Other comprehensive income (loss)	6,721
Stock options exercised	2,058	56	2,002
Stock issued to directors	0	23	(23)
Shares issued for employees stock purchase plan	858	23	835
Shares issued for restricted stock, net of cancellations for tax withholding	(1,288)	55	(1,343)
Shares repurchased	(7,995)	(141)	(7,854)
Stock-based compensation expense	8,537		8,537
Balance, End of Period at Sep. 30, 2016	$ 629,843	$ 17,973	$ 114,171	$ 579,436	$ (81,737)