Segment Information - Reconciliation of Segment Gross Contribution to Net Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Costs and expenses:
Cost of services and product development - unallocated	$ 332,207	$ 223,122	$ 921,820	$ 666,585
Selling, general and administrative	421,163	269,902	1,133,633	799,322
Acquisition and integration charges	30,500	16,557	142,104	32,958
Operating (loss) income	(24,349)	48,726	(69,223)	196,454
Interest expense and other, net	37,591	3,978	86,971	14,208
(Benefit) provision for income taxes	(13,760)	14,264	(52,166)	55,149
Net (loss) income	(48,180)	30,484	(104,028)	127,097
Reportable segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment gross contribution	499,636	355,390	$ 1,387,289	1,088,960
Reportable segments | Maximum
Costs and expenses:
Percent of target bonus allocated to segments			100.00%
Corporate and other expenses
Costs and expenses:
Cost of services and product development - unallocated	3,758	4,453	$ 12,124	14,222
Selling, general and administrative	421,163	269,902	1,133,633	799,322
Depreciation and amortization	68,564	15,752	168,651	46,004
Acquisition and integration charges	$ 30,500	$ 16,557	$ 142,104	$ 32,958