Restructuring (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended	24 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring charges incurred			$ 6,700		$ 19,000	$ 62,600
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2019			10,981
Costs incurred	$ (300)	$ (732)	6,879	$ 14,442
Cash disbursements			(17,200)
Balance as of September 30, 2019	660		660		660	660
Employee Severance and Related Benefits
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2019			10,508
Costs incurred			6,825
Cash disbursements			(16,839)
Balance as of September 30, 2019	494		494		494	494
Software Charges
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2019			198
Costs incurred			0
Cash disbursements			(99)
Balance as of September 30, 2019	99		99		99	99
Excess Facilities, Contract Terminations and Other
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2019			275
Costs incurred			54
Cash disbursements			(262)
Balance as of September 30, 2019	$ 67		$ 67		$ 67	$ 67