Consolidated Statements of Stockholders’ Equity (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Balance	$ 581,054	$ 513,578	$ 497,846	$ 417,347
Net income	65,323	60,032	80,017
Treasury shares purchased at cost	(6,713)	(50,145)
Employee stock options, restricted stock and employee stock purchase plan	6,187	698	3,147
Stock-based compensation expense	9,699	7,103	4,535
Income tax effect, net, of employee stock related activity	1,730	(433)	592
Foreign currency translation	(8,750)	(1,523)	(7,792)
Common Stock [Member]
Balance	980	957	945	931
Employee stock options, restricted stock and employee stock purchase plan	23	12	14
Additional Paid-in Capital [Member]
Balance	504,675	484,962	477,204	468,503
Employee stock options, restricted stock and employee stock purchase plan	8,284	1,088	3,574
Stock-based compensation expense	9,699	7,103	4,535
Income tax effect, net, of employee stock related activity	1,730	(433)	592
Accumulated Other Comprehensive Income (Loss) [Member]
Balance	(9,484)	(734)	789	8,581
Foreign currency translation	(8,750)	(1,523)	(7,792)
Retained Earnings [Member]
Balance	160,338	95,015	34,983	(45,034)
Net income	65,323	60,032	80,017
Treasury Stock [Member]
Balance	(75,455)	(66,622)	(16,075)	(15,634)
Treasury shares purchased at cost	(6,713)	(50,145)
Employee stock options, restricted stock and employee stock purchase plan	$ (2,120)	$ (402)	$ (441)