Condensed Consolidated Statements of Changes in Shareholders' Equity - 6 months ended Jun. 30, 2015 - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2014	$ 658,218	$ 433	$ 279,288	$ 400,514	$ (20,561)	$ (1,456)
Beginning Balance, shares at Dec. 31, 2014		43,291
Issuance of common stock	0	$ 0	0	0	0	0
Issuance of common stock, shares		30
Stock-based compensation expense	3,284		3,284
Excess tax benefit (deficiency) from stock-based compensation	169		169
Net vesting (forfeitures) of common stock and restricted stock under equity award plans	(1,269)	$ 2	(1,110)			(161)
Net vesting (forfeitures) of common stock and restricted stock under equity award plans, shares		200
Repurchase of common stock	(11,969)					(11,969)
Comprehensive income (loss)	12,337			28,551	(16,214)
Ending Balance at Jun. 30, 2015	$ 660,770	$ 435	$ 281,631	$ 429,065	$ (36,775)	$ (13,586)
Ending Balance, shares at Jun. 30, 2015		43,521