Stock-Based Compensation - Stock-based Compensation Expense by Award Type and Expense Category (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 50.2	$ 50.5
Cost of services and product development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	20.6	19.5
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	29.6	31.0
Stock appreciation rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	3.4	4.6
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	46.6	45.6
Common stock equivalents
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	0.2	0.3
Retirement Eligible Employees Equity Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 28.0	$ 30.6