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, 2016		42,037
Beginning Balance at Dec. 31, 2016	$ 1,207,358	$ 420	$ 416,816	$ 941,001	$ (150,879)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	107,962			107,962
Other comprehensive income:
Cumulative translation adjustment	30,664				30,664
Issuance of common stock in connection with:
Exercise of options (in shares)		123
Exercise of options	4,133	$ 1	4,132
Restricted share grants (in shares)		243
Restricted share grants	(4,440)	$ 2	(4,442)
Stock units issued under incentive compensation plan	1,547		1,547
Purchase and retirement of common stock (in shares)		(4,674)
Purchase and retirement of common stock	(168,094)	$ (46)	(168,048)
Cumulative effect due to adoption of new accounting standard	(3,189)		0	(3,189)
Share-based compensation	16,030		16,030
Ending Balance (in shares) at Dec. 31, 2017		37,729
Ending Balance at Dec. 31, 2017	1,191,971	$ 377	266,035	1,045,774	(120,215)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	150,611			150,611
Other comprehensive income:
Cumulative translation adjustment	(27,602)				(27,602)
Issuance of common stock in connection with:
Exercise of options (in shares)		1,051
Exercise of options	41,568	$ 11	41,557
Restricted share grants (in shares)		319
Restricted share grants	(3,094)	$ 3	(3,097)
Stock units issued under incentive compensation plan	1,059		1,059
Purchase and retirement of common stock (in shares)		(952)
Purchase and retirement of common stock	(55,738)	$ (10)	(55,728)
Cumulative effect due to adoption of new accounting standard	342			342
Conversion feature of convertible senior notes, due 2023, net	34,131		34,131
Share-based compensation	$ 15,577		15,577
Ending Balance (in shares) at Dec. 31, 2018	38,147	38,147
Ending 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	216,726			216,726
Other comprehensive income:
Cumulative translation adjustment	$ 6,970				6,970
Issuance of common stock in connection with:
Exercise of options (in shares)	256	256
Exercise of options	$ 9,688	$ 3	9,685
Restricted share grants (in shares)		245
Restricted share grants	(6,517)	$ 3	(6,520)
Stock units issued under incentive compensation plan	1,413		1,413
Purchase and retirement of common stock (in shares)		(1,258)
Purchase and retirement of common stock	(105,941)	$ (13)	(105,928)
Share-based compensation	$ 17,978		17,978
Ending Balance (in shares) at Dec. 31, 2019	37,390	37,390
Ending Balance at Dec. 31, 2019	$ 1,489,142	$ 374	$ 216,162	$ 1,413,453	$ (140,847)