Income Taxes - Current and Deferred (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal									$ (1,711)	$ (423)	$ (9,918)
State									249	1,072	(624)
Foreign									10,300	11,490	8,975
Total									8,838	12,139	(1,567)
Deferred:
Federal									736	25,797	(12,687)
State									57	7,694	(2,217)
Foreign									(223)	335	(851)
Total									570	33,826	(15,755)
Total, income tax expense (benefit)	$ 2,577	$ 2,530	$ 2,781	$ 1,520	$ 2,000	$ 45,012	$ 444	$ (1,491)	9,408	45,965	(17,322)
Components of (Loss) income before income taxes
U.S.									(57,502)	(56,465)	(81,579)
Foreign									67,601	62,990	38,339
Income (loss) before income tax expense (benefit)	1,697	$ 2,759	$ (254)	$ 5,897	(418)	(1,955)	5,087	$ 3,811	10,099	6,525	$ (43,240)
Deferred tax assets:
Compensation and benefits	6,427				5,912				6,427	5,912
Net operating loss and capital loss carryover	17,555				18,974				17,555	18,974
Share-based compensation	5,548				5,092				5,548	5,092
Research and development credits	8,215				7,438				8,215	7,438
Foreign tax credits	10,240				11,117				10,240	11,117
Tax benefits on uncertain tax positions	697				831				697	831
Goodwill and definite-lived intangibles	4,007				6,363				4,007	6,363
Depreciation	3,969				3,527				3,969	3,527
Capitalized software	3,132				383				3,132	383
Rent	2,844				3,013				2,844	3,013
Other	1,297				700				1,297	700
Total deferred tax assets	63,931				63,350				63,931	63,350
Less: valuation allowance	(58,879)				(58,448)				(58,879)	(58,448)
Total deferred tax assets, net of valuation allowance	5,052				4,902				5,052	4,902
Deferred tax liabilities:
Indefinite-lived intangibles	(1,859)				(1,695)				(1,859)	(1,695)
Other	(328)				(55)				(328)	(55)
Total deferred tax liabilities	(2,187)				(1,750)				(2,187)	(1,750)
Net deferred tax assets	2,865				$ 3,152		$ 42,300		2,865	$ 3,152
Increase (decrease) in valuation allowance						48,100			$ (400)
Corporate income tax rate as a percentage					35.00%				21.00%	35.00%	35.00%
Valuation allowance	$ 58,879				$ 58,448				$ 58,879	$ 58,448
U.S.
Deferred tax assets:
Less: valuation allowance						(42,300)
Deferred tax liabilities:
Increase (decrease) in valuation allowance					$ (900)
Valuation allowance						$ 42,300