Segment Information - Reconciliation of Segment Gross Contribution to Net Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Costs and expenses:
Cost of services and product development	$ 334,467	$ 341,278
Selling, general and administrative	487,255	496,639
Acquisition and integration charges	640	1,560
Operating income	225,412	124,718
Interest expense and other, net	(10,659)	(27,864)
Less: Provision for income taxes	50,653	21,757
Net income	164,100	75,097
Reportable segments
Costs and expenses:
Operating income	$ 777,366	676,791
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	$ 7,795	(822)
Selling, general and administrative	487,255	496,639
Depreciation and amortization	56,264	54,696
Acquisition and integration charges	640	1,560
Operating income	$ (551,954)	$ (552,073)