CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Capital Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance at Dec. 31, 2013	$ 555,527	$ 17,855	$ 110,577	$ 438,545	$ (11,450)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	45,870			45,870
Other comprehensive income (loss)	(24,931)				(24,931)
Stock options exercised	15,595	351	15,244
Stock issued to directors		16	(16)
Issuance of stock under stock plans and other	694	17	677
Shares issued for restricted stock	(1,427)	47	(1,474)
Stock-based compensation expense	5,652		5,652
Ending Balance at Sep. 30, 2014	$ 596,980	$ 18,286	$ 130,660	$ 484,415	$ (36,381)