Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions | 3 Months Ended |
Mar. 31, 2020 | Mar. 31, 2019 |
Disaggregation of Revenue [Line Items] | | |
Revenue | $ 4,619.1 | $ 5,044.9 |
Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 4,524.6 | 4,931.5 |
Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 94.5 | 113.4 |
Staffing and Interim | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 4,035.7 | 4,452.4 |
Outcome-Based Solutions and Consulting | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 374 | 358.8 |
Permanent Recruitment | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 133.3 | 149.1 |
Other | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 76.1 | 84.6 |
Americas | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 1,011 | 1,030.2 |
Americas | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 994.3 | 1,013.2 |
Americas | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 16.7 | 17 |
Americas | United States | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 610.9 | 623.2 |
Americas | United States | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 597.8 | 610.2 |
Americas | United States | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 13.1 | 13 |
Americas | Other Americas | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 400.1 | 407 |
Americas | Other Americas | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 396.5 | 403 |
Americas | Other Americas | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 3.6 | 4 |
Americas | Staffing and Interim | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 898.2 | 914.1 |
Americas | Staffing and Interim | United States | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 518.7 | 528.7 |
Americas | Staffing and Interim | Other Americas | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 379.5 | 385.4 |
Americas | Outcome-Based Solutions and Consulting | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 42.5 | 47.4 |
Americas | Outcome-Based Solutions and Consulting | United States | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 30.1 | 34.9 |
Americas | Outcome-Based Solutions and Consulting | Other Americas | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 12.4 | 12.5 |
Americas | Permanent Recruitment | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 30.5 | 28.7 |
Americas | Permanent Recruitment | United States | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 25 | 22.9 |
Americas | Permanent Recruitment | Other Americas | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 5.5 | 5.8 |
Americas | Other | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 39.8 | 40 |
Americas | Other | United States | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 37.1 | 36.7 |
Americas | Other | Other Americas | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 2.7 | 3.3 |
Southern Europe | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 1,944.7 | 2,108.8 |
Southern Europe | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 1,913.6 | 2,073.9 |
Southern Europe | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 31.1 | 34.9 |
Southern Europe | France | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 1,093.8 | 1,306.1 |
Southern Europe | France | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 1,082.1 | 1,292.4 |
Southern Europe | France | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 11.7 | 13.7 |
Southern Europe | Italy | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 327.7 | 356.4 |
Southern Europe | Italy | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 320 | 347.1 |
Southern Europe | Italy | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 7.7 | 9.3 |
Southern Europe | Other Southern Europe | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 523.2 | 446.3 |
Southern Europe | Other Southern Europe | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 511.5 | 434.4 |
Southern Europe | Other Southern Europe | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 11.7 | 11.9 |
Southern Europe | Staffing and Interim | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 1,721.3 | 1,901.5 |
Southern Europe | Staffing and Interim | France | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 998.3 | 1,224.5 |
Southern Europe | Staffing and Interim | Italy | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 307.1 | 330 |
Southern Europe | Staffing and Interim | Other Southern Europe | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 415.9 | 347 |
Southern Europe | Outcome-Based Solutions and Consulting | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 177.4 | 149.1 |
Southern Europe | Outcome-Based Solutions and Consulting | France | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 78.1 | 58.7 |
Southern Europe | Outcome-Based Solutions and Consulting | Italy | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 8.7 | 9.8 |
Southern Europe | Outcome-Based Solutions and Consulting | Other Southern Europe | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 90.6 | 80.6 |
Southern Europe | Permanent Recruitment | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 34.6 | 38.6 |
Southern Europe | Permanent Recruitment | France | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 12.5 | 14.5 |
Southern Europe | Permanent Recruitment | Italy | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 8.2 | 9.9 |
Southern Europe | Permanent Recruitment | Other Southern Europe | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 13.9 | 14.2 |
Southern Europe | Other | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 11.4 | 19.6 |
Southern Europe | Other | France | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 4.9 | 8.4 |
Southern Europe | Other | Italy | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 3.7 | 6.7 |
Southern Europe | Other | Other Southern Europe | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 2.8 | 4.5 |
Northern Europe | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 1,068.5 | 1,200.5 |
Northern Europe | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 1,041.4 | 1,167.4 |
Northern Europe | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 27.1 | 33.1 |
Northern Europe | Staffing and Interim | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 949.6 | 1,053.4 |
Northern Europe | Outcome-Based Solutions and Consulting | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 70.9 | 91.5 |
Northern Europe | Permanent Recruitment | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 31.3 | 38.1 |
Northern Europe | Other | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 16.7 | 17.5 |
APME | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 594.9 | 705.4 |
APME | Services transferred over time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 575.3 | 677 |
APME | Services transferred at a point in time | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 19.6 | 28.4 |
APME | Staffing and Interim | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 466.6 | 583.4 |
APME | Outcome-Based Solutions and Consulting | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 83.2 | 70.8 |
APME | Permanent Recruitment | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | 36.9 | 43.7 |
APME | Other | | |
Disaggregation of Revenue [Line Items] | | |
Revenue | $ 8.2 | $ 7.5 |