Restructuring - Summary of Accruals of Restructuring Programs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring (Reversals) Expenses, Net	$ (882)	$ 13,445	$ 24	$ 13,772
Contractual Lease Obligations
Restructuring Cost and Reserve [Line Items]
Restructuring (Reversals) Expenses, Net	207	11,841	926	11,318
Restructuring Reserve [Roll Forward]
Balance at January 1, 2018			12,437
Charges			0
Adjustments			926
Restructuring Charges			926
Payments			(3,305)
Balance at June 30, 2018	10,058		10,058
Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring (Reversals) Expenses, Net	87	1,144	601	1,590
Restructuring Reserve [Roll Forward]
Balance at January 1, 2018			2,303
Charges			601
Adjustments			0
Restructuring Charges			601
Payments			(1,571)
Balance at June 30, 2018	$ 1,333		$ 1,333
DAMI | Restructuring Program 2016
Restructuring Cost and Reserve [Line Items]
Restructuring (Reversals) Expenses, Net		$ 100		$ 200