Restructuring Activities - Narrative (Details) $ in Thousands			3 Months Ended		9 Months Ended
	Aug. 10, 2018 USD ($)	Dec. 14, 2015 USD ($) employee	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 3,055	$ 3,142	$ 10,687	$ 3,142
Restructuring Plan, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges					10,687
Non-cash settlements/adjustments	$ 400				112
Restructuring charges recognized pursuant to 2018 plan			$ 16,700		16,700
Restructuring Plan, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 6,700
Expected number of positions eliminated | employee		100
Employee Severance and Related Benefits | Restructuring Plan, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges					4,434
Non-cash settlements/adjustments					(55)
Employee Severance and Related Benefits | Restructuring Plan, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 5,600
Lease and Contract Termination Costs | Restructuring Plan, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges					851
Non-cash settlements/adjustments					$ 167
Lease and Contract Termination Costs | Restructuring Plan, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 1,100
Minimum | Restructuring Plan, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges	20,000
Minimum | Employee Severance and Related Benefits | Restructuring Plan, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges	12,000
Minimum | Lease and Contract Termination Costs | Restructuring Plan, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges	8,000
Maximum | Restructuring Plan, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges	25,000
Maximum | Employee Severance and Related Benefits | Restructuring Plan, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges	15,000
Maximum | Lease and Contract Termination Costs | Restructuring Plan, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 10,000