Consolidated Statements Of 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 Loss [Member]
Balances, shares at Dec. 31, 2014	52,994	52,994
Balances, value at Dec. 31, 2014	$ 1,291,040	$ 5,300	$ 649,715	$ 645,500	$ (9,475)
Stock-based compensation expense	4,020	$ 0	4,020	0	0
Shares repurchased and retired, shares		(1,461)
Shares repurchased and retired, value	(34,558)	$ (147)	(15,952)	(18,459)	0
Stock options exercised, shares		80
Stock options exercised, value	1,471	$ 8	1,463	0	0
Vesting of restricted stock units, shares		141
Vesting of restricted stock units, value	0	$ 14	(14)	0	0
Shares withheld for taxes, shares		(24)
Shares withheld for taxes, value	(571)	$ (2)	(569)	0	0
Excess tax benefit of stock-based compensation	313	0	313	0	0
Comprehensive income	$ 32,611	$ 0	0	35,415	(2,804)
Balances, shares at Jun. 30, 2015	51,730	51,730
Balances, value at Jun. 30, 2015	$ 1,294,326	$ 5,173	$ 638,976	$ 662,456	$ (12,279)