Consolidated Statements of Stockholders Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2011	$ 320,577	$ 1,486	$ 56,796	$ (35,348)	$ 300,877	$ (3,234)
Balance, Shares at Dec. 31, 2011		13,871,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options, shares issued		526,000
Employee stock purchase plan, shares issued		61,000
Exercise of stock options, value	19,411	0	1,348	18,063
Proceeds from employee stock purchase plan	2,220	0	63	2,157
Stock compensation	5,563		5,563
Foreign Currency Translation Adjustment	1,805					1,805
Net Income	41,281				41,281
Balance at Dec. 31, 2012	390,857	1,486	63,770	(15,128)	342,158	(1,429)
Balance, Shares at Dec. 31, 2012		14,458,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options, shares issued		733,000
Treasury Stock, Shares		(140,000)
Employee stock purchase plan, shares issued		51,000
Exercise of stock options, value	24,970	24	2,030	22,916
Treasury Stock, Value	(3,033)		6,678	(9,711)
Proceeds from employee stock purchase plan	2,457	0	583	1,874
Stock compensation	5,434
Foreign Currency Translation Adjustment	3,622					3,622
Net Income	40,418				40,418
Balance at Dec. 31, 2013	464,725	1,510	78,495	(49)	382,576	2,193
Balance, Shares at Dec. 31, 2013	15,102,000	15,102,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options, shares issued		544,000
Treasury Stock, Shares		(98,000)
Employee stock purchase plan, shares issued		47,000
Exercise of stock options, value	22,698	48	18,528	4,122
Treasury Stock, Value	(5,836)		285	(6,121)
Proceeds from employee stock purchase plan	2,485	1	436	2,048
Stock compensation	9,592
Foreign Currency Translation Adjustment	(11,747)					(11,747)
Net Income	26,335				26,335
Balance at Dec. 31, 2014	$ 508,252	$ 1,559	$ 107,336	$ 0	$ 408,911	$ (9,554)
Balance, Shares at Dec. 31, 2014	15,595,000	15,595,000