Consolidated Statements of Stockholders Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance, Shares at Dec. 31, 2012		14,458,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock and exercise of stock options, shares issued		733,000
Treasury Stock, Shares		(140,000)
Employee stock purchase plan, shares issued		51,000
Balance, Shares at Dec. 31, 2013		15,102,000
Balance at Dec. 31, 2012	$ 390,857	$ 1,486	$ 63,770	$ (15,128)	$ 342,158	$ (1,429)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock and 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		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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock and exercise of stock options, shares issued		544,000
Treasury Stock, Shares		(98,000)
Employee stock purchase plan, shares issued		47,000
Balance, Shares at Dec. 31, 2014	15,595,000	15,595,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock and 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		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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock and exercise of stock options, shares issued		475,000
Treasury Stock, Shares		(18,000)
Employee stock purchase plan, shares issued		34,000
Balance, Shares at Dec. 31, 2015	16,086,000	16,086,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock and exercise of stock options, value	$ 24,372	$ 46	22,715	1,611
Treasury Stock, Value	(1,523)		88	(1,611)
Proceeds from employee stock purchase plan	2,162	3	2,159	0
Stock compensation	12,827		12,827
Foreign Currency Translation Adjustment	(11,204)					(11,204)
Net Income	44,985				44,985
Balance at Dec. 31, 2015	$ 579,871	$ 1,608	$ 145,125	$ 0	$ 453,896	$ (20,758)