Condensed Consolidated Statements of Stockholders' Equity Statement - USD ($) $ in Thousands	Total	Common Stock Shares [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]
Common stock, shares outstanding at Dec. 31, 2018		20,492,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2018	$ 1,263,655		$ 2,049	$ 657,899	$ (95)	$ 620,747	$ (16,945)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, New Issues		254,000
Stock Issued During Period, Value, New Issues	925		18		5,196
Adjustments to Additional Paid in Capital, Other				(4,289)
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		(78,000)
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(18,157)				(18,157)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	6,209			6,209
Other Comprehensive (Loss) Income, Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(936)
Net Income Attributable to Parent	30,998					30,998
Stockholders' Equity Attributable to Parent at Mar. 31, 2019	1,282,694		2,067	659,819	(13,056)	651,745	(17,881)
Common stock, shares outstanding at Mar. 31, 2019		20,668,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive income (loss), net of Tax	(936)						(936)
Common stock, shares outstanding at Dec. 31, 2018		20,492,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2018	$ 1,263,655		2,049	657,899	(95)	620,747	(16,945)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation	(79,313)
Stockholders' Equity Attributable to Parent at Sep. 30, 2019	$ 1,340,335		2,067	659,709	0	701,141	(22,582)
Common stock, shares outstanding at Sep. 30, 2019		20,671,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive income (loss), net of Tax	(5,637)
Common stock, shares outstanding at Mar. 31, 2019		20,668,000
Stockholders' Equity Attributable to Parent at Mar. 31, 2019	1,282,694		2,067	659,819	(13,056)	651,745	(17,881)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, New Issues		0
Stock Issued During Period, Value, New Issues	3,009		0		11,514
Adjustments to Additional Paid in Capital, Other				(8,505)
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		0
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(108)				(108)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	6,229			6,229
Other Comprehensive (Loss) Income, Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	3,207
Net Income Attributable to Parent	22,833					22,833
Stockholders' Equity Attributable to Parent at Jun. 30, 2019	1,317,864		2,067	657,543	(1,650)	674,578	(14,674)
Common stock, shares outstanding at Jun. 30, 2019		20,668,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive income (loss), net of Tax	3,207						3,207
Stock Issued During Period, Shares, New Issues		4,000
Stock Issued During Period, Value, New Issues	307		0		1,863
Adjustments to Additional Paid in Capital, Other				(1,556)
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		(1,000)
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(213)				(213)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	3,722			3,722
Other Comprehensive (Loss) Income, Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(7,908)
Net Income Attributable to Parent	26,563					26,563
Stockholders' Equity Attributable to Parent at Sep. 30, 2019	1,340,335		2,067	659,709	0	701,141	(22,582)
Common stock, shares outstanding at Sep. 30, 2019		20,671,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive income (loss), net of Tax	$ (7,908)						(7,908)
Common stock, shares outstanding at Dec. 31, 2019	20,742,000	20,742,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2019	$ 1,377,244		2,074	668,947	(157)	721,782	(15,402)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, New Issues		155,000
Stock Issued During Period, Value, New Issues	560		9		10,758
Adjustments to Additional Paid in Capital, Other				(10,207)
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		(64,000)
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(12,174)				(12,174)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	6,939			6,939
Other Comprehensive (Loss) Income, Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(13,510)
Net Income Attributable to Parent	16,834					16,834
Stockholders' Equity Attributable to Parent at Mar. 31, 2020	1,375,893		2,083	665,679	(1,573)	738,616	(28,912)
Common stock, shares outstanding at Mar. 31, 2020		20,833,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive income (loss), net of Tax	$ (13,510)						(13,510)
Common stock, shares outstanding at Dec. 31, 2019	20,742,000	20,742,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2019	$ 1,377,244		2,074	668,947	(157)	721,782	(15,402)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation	(66,749)
Stockholders' Equity Attributable to Parent at Sep. 30, 2020	$ 1,452,220		2,097	683,326	(180)	782,510	(15,533)
Common stock, shares outstanding at Sep. 30, 2020	20,968,000	20,969,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive income (loss), net of Tax	$ (131)
Common stock, shares outstanding at Mar. 31, 2020		20,833,000
Stockholders' Equity Attributable to Parent at Mar. 31, 2020	1,375,893		2,083	665,679	(1,573)	738,616	(28,912)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, New Issues		106,000
Stock Issued During Period, Value, New Issues	6,239		11		1,820
Adjustments to Additional Paid in Capital, Other				4,408
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		(2,000)
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(387)				(387)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	5,410			5,410
Other Comprehensive (Loss) Income, Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	5,734
Net Income Attributable to Parent	18,908					18,908
Stockholders' Equity Attributable to Parent at Jun. 30, 2020	1,411,797		2,094	675,497	(140)	757,524	(23,178)
Common stock, shares outstanding at Jun. 30, 2020		20,937,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive income (loss), net of Tax	5,734						5,734
Stock Issued During Period, Shares, New Issues		33,000
Stock Issued During Period, Value, New Issues	1,787		3		220
Adjustments to Additional Paid in Capital, Other				1,564
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		(1,000)
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(260)				(260)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	6,265			6,265
Other Comprehensive (Loss) Income, Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	7,645
Net Income Attributable to Parent	24,986					24,986
Stockholders' Equity Attributable to Parent at Sep. 30, 2020	$ 1,452,220		$ 2,097	$ 683,326	$ (180)	$ 782,510	(15,533)
Common stock, shares outstanding at Sep. 30, 2020	20,968,000	20,969,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive income (loss), net of Tax	$ 7,645						$ 7,645