Stock-Based Compensation - Stock-based Compensation Expense by Award Type and Expense Category (Details) - USD ($) $ in Millions			12 Months Ended
	Feb. 03, 2021	Feb. 05, 2020	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			$ 129.8	$ 90.6	$ 98.6
Cost of services and product development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			53.3	32.7	35.0
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			76.5	57.9	63.6
Stock appreciation rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			10.5	8.8	8.2
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			118.2	81.0	89.6
Common stock equivalents
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			1.1	0.8	0.8
Performance-based RSUs | Executives
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense					6.5
Target performance percentage	95.00%	50.00%
Retirement Eligible Employees Equity Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			$ 55.5	$ 32.2	$ 41.2