Statement of Stockholders Equity (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stockholders' Equity Attributable to Parent	$ 474,965	$ 464,462	$ 474,965	$ 464,462	$ 389,611
Common Stock, Shares, Outstanding	40,613,000	40,503,000	40,613,000	40,503,000
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures			15,831	26,337	3,722
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition			4,993	13,742	12,720
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Settled in Cash			(11,198)
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation			1,576	(1,046)	(811)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax			(23,214)	3,733	1,188
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax			533	(1)	10
Net Income (Loss) Attributable to Parent	9,319	34,355	46,982	32,086	20,581
Comprehensive Income (Loss), Net of Tax, Attributable to Parent			24,301	35,818	21,779
Stock Repurchased and Retired During Period, Value			25,000	0	57,118
Common Stock [Member]
Stockholders' Equity Attributable to Parent	41	41	41	41	38
Common Stock, Shares, Outstanding	40,613,000	40,504,000	40,613,000	40,504,000	37,991,000
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures			1	3	1
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures			1,485,000	2,513,000	691,000
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition			0	0	0
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation			0	0	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax			0	0	0
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax			0	0	0
Net Income (Loss) Attributable to Parent			0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent			0	0	0
Stock Repurchased and Retired During Period, Shares			1,376,000	0	4,656,000
Stock Repurchased and Retired During Period, Value			1	0	5
Additional Paid-in Capital [Member]
Stockholders' Equity Attributable to Parent	237,752	251,550	237,752	251,550	212,520
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures			15,830	26,334	3,721
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition			4,993	13,742	12,720
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Settled in Cash			(11,198)
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation			1,576	(1,046)	(811)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax			0	0	0
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax			0	0	0
Net Income (Loss) Attributable to Parent			0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent			0	0	0
Stock Repurchased and Retired During Period, Value			24,999	0	57,113
Retained Earnings [Member]
Stockholders' Equity Attributable to Parent	226,396	179,414	226,396	179,414	147,328
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures			0	0	0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition			0	0	0
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation			0	0	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax			0	0	0
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax			0	0	0
Net Income (Loss) Attributable to Parent			46,982	32,086	20,581
Comprehensive Income (Loss), Net of Tax, Attributable to Parent			46,982	32,086	20,581
Stock Repurchased and Retired During Period, Value			0	0	0
Accumulated Other Comprehensive Income (Loss) [Member]
Stockholders' Equity Attributable to Parent	10,776	33,457	10,776	33,457	29,725
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures			0	0	0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition			0	0	0
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation			0	0	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax			(23,214)	3,733	1,188
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax			533	(1)	10
Net Income (Loss) Attributable to Parent			0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent			(22,681)	3,732	1,198
Stock Repurchased and Retired During Period, Value			0	0	0
Balance, as corrected [Member]
Stockholders' Equity Attributable to Parent						409,319
Balance, as corrected [Member] | Common Stock [Member]
Stockholders' Equity Attributable to Parent						42
Common Stock, Shares, Outstanding						41,956,000
Balance, as corrected [Member] | Additional Paid-in Capital [Member]
Stockholders' Equity Attributable to Parent						254,003
Balance, as corrected [Member] | Retained Earnings [Member]
Stockholders' Equity Attributable to Parent						126,747
Balance, as corrected [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Stockholders' Equity Attributable to Parent						$ 28,527