Restructuring - Summary of Accruals of Restructuring Programs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring Expenses, Net	$ 537	$ 845	$ 561	$ 14,617
Contractual Lease Obligations
Restructuring Cost and Reserve [Line Items]
Restructuring Expenses, Net	586	694	1,512	12,011
Restructuring Reserve [Roll Forward]
Balance at January 1, 2018			12,437
Charges			0
Adjustments			1,512
Restructuring Charges			1,512
Payments			(4,559)
Balance at September 30, 2018	9,390		9,390
Severance
Restructuring Cost and Reserve [Line Items]
Restructuring Expenses, Net	0	$ (285)	601	1,306
Restructuring Reserve [Roll Forward]
Balance at January 1, 2018			2,303
Charges			601
Adjustments			0
Restructuring Charges			601
Payments			(1,895)
Balance at September 30, 2018	$ 1,009		$ 1,009
DAMI | Restructuring Program 2016
Restructuring Cost and Reserve [Line Items]
Restructuring Expenses, Net				$ 300