Restructuring - Summary of Accruals of Restructuring Programs (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Restructuring Reserve [Roll Forward]
Charges		$ 845	$ 4,658	$ 14,617	$ 4,658
Contractual Lease Obligations
Restructuring Reserve [Roll Forward]
Balance at January 1, 2017				10,583
Charges		694		12,676
Adjustments	[1]			(665)
Restructuring Charges				12,011
Payments				(9,594)
Balance at September 30, 2017		13,000		13,000
Severance
Restructuring Reserve [Roll Forward]
Balance at January 1, 2017				2,079
Charges				1,306
Adjustments	[1]			0
Restructuring Charges				1,306
Payments				(2,176)
Balance at September 30, 2017		$ 1,209		$ 1,209

[1] Adjustments relate to early buyouts of leases, changes in sublease assumptions and interest accretion.