Restructuring - Summary of Restructuring Liability (Details) - USD ($) $ in Thousands	12 Months Ended			36 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017
Restructuring Reserve [Roll Forward]
Balance - Beginning of the year	$ 2,274	$ 585
Provisions	1,598	3,507	$ 800	$ 5,900
Utilizations	(3,829)	(1,818)
Balance - End of the year	43	2,274	585	43
Employee Costs
Restructuring Reserve [Roll Forward]
Balance - Beginning of the year	2,229	542
Provisions	196	2,668
Utilizations	(2,382)	(981)
Balance - End of the year	43	2,229	542	43
Facility Exit and Other Contractual Costs
Restructuring Reserve [Roll Forward]
Balance - Beginning of the year	45	43
Provisions	1,402	839
Utilizations	(1,447)	(837)
Balance - End of the year	$ 0	$ 45	$ 43	$ 0