Restructuring (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Reserve [Roll Forward]
Balance		$ 14,243,000	$ 1,613,000	$ 387,000
Costs incurred		27,594,000	54,884,000	10,301,000
Cash disbursements		(24,854,000)	(9,110,000)	(4,488,000)
Software and other non-cash charges		(6,529,000)	(33,144,000)	(4,587,000)
Translation adjustments and other		527,000
Balance	$ 14,243,000	10,981,000	14,243,000	1,613,000
Employee Severance and Related Benefits
Restructuring Reserve [Roll Forward]
Balance		12,857,000	1,444,000	162,000
Costs incurred		15,841,000	17,311,000	5,714,000
Cash disbursements		(18,922,000)	(5,898,000)	(4,432,000)
Software and other non-cash charges		0	0	0
Translation adjustments and other		732,000
Balance	12,857,000	10,508,000	12,857,000	1,444,000
Software Charges
Restructuring Reserve [Roll Forward]
Balance		0	0	0
Costs incurred		4,940,000	31,965,000	4,587,000
Cash disbursements		0	0	0
Software and other non-cash charges		(4,742,000)	(31,965,000)	(4,587,000)
Translation adjustments and other		0
Balance	0	198,000	0	0
Excess Facilities, Contract Terminations and Other
Restructuring Reserve [Roll Forward]
Balance		1,386,000	169,000	225,000
Costs incurred		6,813,000	5,608,000	0
Cash disbursements		(5,932,000)	(3,212,000)	(56,000)
Software and other non-cash charges		(1,787,000)	(1,179,000)	0
Translation adjustments and other		(205,000)
Balance	1,386,000	275,000	1,386,000	169,000
2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges recognized		12,300,000
Expected restructuring charge		12,000,000
2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges recognized	$ 13,400,000	$ 62,700,000
2016 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges recognized			$ 9,700,000
Expected restructuring charge				$ 0