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Stock-Based Compensation - Stock-based Compensation Expense by Award Type and Expense Category (Details) - USD ($) $ in Millions | 3 Months Ended |
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Mar. 31, 2022 | Mar. 31, 2021 | Feb. 03, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Total stock-based compensation expense (credit) | $ 32.1 | $ 36.1 |
Cost of services and product development |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Total stock-based compensation expense (credit) | 11.5 | 13.7 |
Selling, general and administrative |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Total stock-based compensation expense (credit) | 20.6 | 22.4 |
Stock appreciation rights |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Total stock-based compensation expense (credit) | 1.9 | 2.0 |
Restricted stock units |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Total stock-based compensation expense (credit) | 30.0 | 33.9 |
Common stock equivalents |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Total stock-based compensation expense (credit) | 0.2 | 0.2 |
Retirement eligible employees equity award |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Total stock-based compensation expense (credit) | 19.2 | $ 21.5 |
Performance-based RSUs | Executive officer |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Total stock-based compensation expense (credit) | $ 6.5 |  |
Target performance percentage | 50.00% |  | 95.00%

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