Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance (in shares) at Dec. 31, 2018		38,147
Beginning Balance at Dec. 31, 2018	$ 1,348,825	$ 381	$ 299,534	$ 1,196,727	$ (147,817)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	62,645			62,645
Other comprehensive loss:
Cumulative translation adjustment	5,223				5,223
Issuance of common stock in connection with:
Exercise of options (in shares)		55
Exercise of options	2,212	$ 1	2,211
Restricted share grants, less net settled shares (in shares)		153
Restricted share grants, less net settled shares	(2,739)	$ 1	(2,740)
Stock units issued under incentive compensation plan	1,346		1,346
Purchase and retirement of common stock (in shares)		(328)
Purchase and retirement of common stock	(21,883)	$ (3)	(21,880)
Share-based compensation	6,393		6,393
Ending Balance (in shares) at Mar. 31, 2019		38,027
Ending Balance at Mar. 31, 2019	$ 1,402,022	$ 380	284,864	1,259,372	(142,594)
Beginning Balance (in shares) at Dec. 31, 2019	37,390	37,390
Beginning Balance at Dec. 31, 2019	$ 1,489,142	$ 374	216,162	1,413,453	(140,847)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	56,747			56,747
Other comprehensive loss:
Cumulative translation adjustment	(31,102)				(31,102)
Issuance of common stock in connection with:
Exercise of options (in shares)		34
Exercise of options	1,207	$ 1	1,206
Restricted share grants, less net settled shares (in shares)		136
Restricted share grants, less net settled shares	(6,767)	$ 1	(6,768)
Stock units issued under incentive compensation plan	2,314		2,314
Purchase and retirement of common stock (in shares)		(450)
Purchase and retirement of common stock	(50,311)	$ (5)	(50,306)
Share-based compensation	$ 7,454		7,454
Ending Balance (in shares) at Mar. 31, 2020	37,110	37,110
Ending Balance at Mar. 31, 2020	$ 1,468,684	$ 371	$ 170,062	$ 1,470,200	$ (171,949)