Restructuring - 2017 Restructuring Textual (Details) $ in Thousands	3 Months Ended								12 Months Ended			17 Months Ended
	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) employee	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2018 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges, pre tax	$ 13,900	$ 7,400	$ 2,900	$ 5,200	$ 17,100	$ 6,700	$ 300	$ (100)
Definite-lived intangible asset impairment									$ 2,169	$ 41,032	$ 0
Allowance for doubtful accounts receivable, write-offs									4,268	3,478	$ 9,509
Restructuring Plan 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges, pre tax												$ 139,700
Restructuring charges net of tax												125,900
Cash									14,800	8,474		25,800
Utilized non-cash									17,372	10,080		113,900
Definite-lived intangible asset impairment												86,400
Allowance for doubtful accounts receivable, write-offs									$ 27,500
Restructuring and related cost, expected number of positions eliminated | employee									360
Restructuring and related cost, expected number of additional positions eliminated | employee									100
Restructuring charges, incurred									$ 29,486	23,743
Restructuring Plan 2017 | Restructuring charges
Restructuring Cost and Reserve [Line Items]
Restructuring charges, incurred									6,894	$ 12,814
Minimum | Restructuring Plan 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	15,000								15,000			15,000
Maximum | Restructuring Plan 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	$ 19,000								$ 19,000			$ 19,000