Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions | 3 Months Ended |
Mar. 31, 2021 | Mar. 31, 2020 |
Disaggregation of Revenue [Line Items] | | |
Revenue | $ 4,924.4 | $ 4,619.1 |
Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 4,829.9 | 4,524.6 |
Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 94.5 | 94.5 |
Staffing and Interim | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 4,310.9 | 4,035.7 |
Outcome-Based Solutions and Consulting | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 388.7 | 374 |
Permanent Recruitment | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 135.7 | 133.3 |
Other | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 89.1 | 76.1 |
Americas | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 1,002.9 | 1,011 |
Americas | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 984.9 | 994.3 |
Americas | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 18 | 16.7 |
Americas | United States | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 608.8 | 610.9 |
Americas | United States | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 594.7 | 597.8 |
Americas | United States | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 14.1 | 13.1 |
Americas | Other Americas | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 394.1 | 400.1 |
Americas | Other Americas | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 390.2 | 396.5 |
Americas | Other Americas | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 3.9 | 3.6 |
Americas | Staffing and Interim | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 885 | 898.2 |
Americas | Staffing and Interim | United States | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 510.1 | 518.7 |
Americas | Staffing and Interim | Other Americas | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 374.9 | 379.5 |
Americas | Outcome-Based Solutions and Consulting | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 38.7 | 42.5 |
Americas | Outcome-Based Solutions and Consulting | United States | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 28.8 | 30.1 |
Americas | Outcome-Based Solutions and Consulting | Other Americas | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 9.9 | 12.4 |
Americas | Permanent Recruitment | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 34.6 | 30.5 |
Americas | Permanent Recruitment | United States | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 28.5 | 25 |
Americas | Permanent Recruitment | Other Americas | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 6.1 | 5.5 |
Americas | Other | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 44.6 | 39.8 |
Americas | Other | United States | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 41.4 | 37.1 |
Americas | Other | Other Americas | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 3.2 | 2.7 |
Southern Europe | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 2,160.3 | 1,944.7 |
Southern Europe | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 2,129.3 | 1,913.6 |
Southern Europe | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 31 | 31.1 |
Southern Europe | France | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 1,188.9 | 1,093.8 |
Southern Europe | France | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 1,176.9 | 1,082.1 |
Southern Europe | France | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 12 | 11.7 |
Southern Europe | Italy | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 402.8 | 327.7 |
Southern Europe | Italy | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 393.5 | 320 |
Southern Europe | Italy | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 9.3 | 7.7 |
Southern Europe | Other Southern Europe | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 568.6 | 523.2 |
Southern Europe | Other Southern Europe | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 558.9 | 511.5 |
Southern Europe | Other Southern Europe | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 9.7 | 11.7 |
Southern Europe | Staffing and Interim | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 1,926.3 | 1,721.3 |
Southern Europe | Staffing and Interim | France | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 1,084 | 998.3 |
Southern Europe | Staffing and Interim | Italy | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 381.5 | 307.1 |
Southern Europe | Staffing and Interim | Other Southern Europe | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 460.8 | 415.9 |
Southern Europe | Outcome-Based Solutions and Consulting | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 186.8 | 177.4 |
Southern Europe | Outcome-Based Solutions and Consulting | France | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 86.5 | 78.1 |
Southern Europe | Outcome-Based Solutions and Consulting | Italy | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 7.7 | 8.7 |
Southern Europe | Outcome-Based Solutions and Consulting | Other Southern Europe | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 92.6 | 90.6 |
Southern Europe | Permanent Recruitment | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 34.2 | 34.6 |
Southern Europe | Permanent Recruitment | France | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 12.8 | 12.5 |
Southern Europe | Permanent Recruitment | Italy | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 9.7 | 8.2 |
Southern Europe | Permanent Recruitment | Other Southern Europe | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 11.7 | 13.9 |
Southern Europe | Other | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 13 | 11.4 |
Southern Europe | Other | France | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 5.6 | 4.9 |
Southern Europe | Other | Italy | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 3.9 | 3.7 |
Southern Europe | Other | Other Southern Europe | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 3.5 | 2.8 |
Northern Europe | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 1,133.8 | 1,068.5 |
Northern Europe | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 1,107.8 | 1,041.4 |
Northern Europe | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 26 | 27.1 |
Northern Europe | Staffing and Interim | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 1,018.8 | 949.6 |
Northern Europe | Outcome-Based Solutions and Consulting | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 64.8 | 70.9 |
Northern Europe | Permanent Recruitment | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 29.5 | 31.3 |
Northern Europe | Other | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 20.7 | 16.7 |
APME | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 627.4 | 594.9 |
APME | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 607.9 | 575.3 |
APME | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 19.5 | 19.6 |
APME | Staffing and Interim | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 480.8 | 466.6 |
APME | Outcome-Based Solutions and Consulting | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 98.4 | 83.2 |
APME | Permanent Recruitment | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 37.4 | 36.9 |
APME | Other | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | $ 10.8 | $ 8.2 |