Segment Information - Reconciliation of Segment Gross Contribution to Net Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Cost of services and product development	$ 346,645	$ 357,209
Costs and expenses:
Selling, general and administrative	518,770	487,745
Acquisition and integration charges	2,772	59,266
Operating income (loss)	48,799	(8,711)
Interest expense and other, net	25,671	34,160
Loss from divested operations	2,075	0
Provision (benefit) for income taxes	258	(23,284)
Net income (loss)	20,795	(19,587)
Reportable segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment gross contribution	$ 622,762	614,814
Reportable segments | Maximum
Costs and expenses:
Percent of target bonus allocated to segments	100.00%
Corporate and other expenses
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Cost of services and product development	$ (1,037)	8,458
Costs and expenses:
Selling, general and administrative	518,770	487,745
Depreciation and amortization	53,458	68,056
Acquisition and integration charges	$ 2,772	$ 59,266