Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
Jun. 30, 2019 | Jun. 30, 2018 | Jun. 30, 2019 | Jun. 30, 2018 |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | $ 5,373.1 | $ 5,656.9 | $ 10,418 | $ 11,179.3 |
Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 5,252.9 | 5,529.8 | 10,184.2 | 10,930.8 |
Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 120.2 | 127.1 | 233.8 | 248.5 |
Staffing and Interim | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 4,759.7 | 5,019.4 | 9,212.1 | 9,915.5 |
Outcome-Based Solutions and Consulting | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 369.3 | 379.1 | 728.1 | 757.6 |
Permanent Recruitment | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 158.9 | 166.7 | 308 | 326.6 |
Other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 85.2 | 91.7 | 169.8 | 179.6 |
Americas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1,043.4 | 1,052.5 | 2,050.7 | 2,075.1 |
Americas | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1,025.4 | 1,034.5 | 2,015.7 | 2,040.9 |
Americas | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 18 | 18 | 35 | 34.2 |
Americas | United States | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 630.9 | 640.5 | 1,234.5 | 1,256.8 |
Americas | United States | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 617.2 | 626.7 | 1,207.8 | 1,231.1 |
Americas | United States | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 13.7 | 13.8 | 26.7 | 25.7 |
Americas | Other Americas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 412.5 | 412 | 816.2 | 818.3 |
Americas | Other Americas | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 408.2 | 407.8 | 807.9 | 809.8 |
Americas | Other Americas | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 4.3 | 4.2 | 8.3 | 8.5 |
Americas | Staffing and Interim | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 944.1 | 951.4 | 1,858.2 | 1,882.8 |
Americas | Staffing and Interim | United States | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 551.3 | 559.1 | 1,080 | 1,102.3 |
Americas | Staffing and Interim | Other Americas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 392.8 | 392.3 | 778.2 | 780.5 |
Americas | Outcome-Based Solutions and Consulting | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 45.4 | 46.9 | 88.1 | 87.4 |
Americas | Outcome-Based Solutions and Consulting | United States | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 33.1 | 34.6 | 64.1 | 63.9 |
Americas | Outcome-Based Solutions and Consulting | Other Americas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 12.3 | 12.3 | 24 | 23.5 |
Americas | Permanent Recruitment | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 30.3 | 30.9 | 59 | 58.7 |
Americas | Permanent Recruitment | United States | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 24.1 | 24.4 | 47 | 46.2 |
Americas | Permanent Recruitment | Other Americas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 6.2 | 6.5 | 12 | 12.5 |
Americas | Other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 23.6 | 23.3 | 45.4 | 46.2 |
Americas | Other | United States | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 22.4 | 22.4 | 43.4 | 44.4 |
Americas | Other | Other Americas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1.2 | 0.9 | 2 | 1.8 |
Southern Europe | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 2,387.2 | 2,434 | 4,489.4 | 4,746 |
Southern Europe | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 2,351.5 | 2,398.6 | 4,418.7 | 4,675.1 |
Southern Europe | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 35.7 | 35.4 | 70.7 | 70.9 |
Southern Europe | France | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1,420.2 | 1,512.5 | 2,721.6 | 2,936.5 |
Southern Europe | France | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1,407.5 | 1,498.5 | 2,695.2 | 2,908.1 |
Southern Europe | France | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 12.7 | 14 | 26.4 | 28.4 |
Southern Europe | Italy | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 394 | 443 | 749.9 | 856.6 |
Southern Europe | Italy | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 384.2 | 433.5 | 730.7 | 838.4 |
Southern Europe | Italy | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 9.8 | 9.5 | 19.2 | 18.2 |
Southern Europe | Other Southern Europe | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 573 | 478.5 | 1,017.9 | 952.9 |
Southern Europe | Other Southern Europe | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 559.8 | 466.6 | 992.8 | 928.6 |
Southern Europe | Other Southern Europe | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 13.2 | 11.9 | 25.1 | 24.3 |
Southern Europe | Staffing and Interim | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 2,182.8 | 2,234.5 | 4,084.3 | 4,344.8 |
Southern Europe | Staffing and Interim | France | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1,345.7 | 1,436.8 | 2,570.2 | 2,781.4 |
Southern Europe | Staffing and Interim | Italy | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 365.2 | 413.9 | 695.2 | 800.9 |
Southern Europe | Staffing and Interim | Other Southern Europe | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 471.9 | 383.8 | 818.9 | 762.5 |
Southern Europe | Outcome-Based Solutions and Consulting | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 151.6 | 144.6 | 298.5 | 292.9 |
Southern Europe | Outcome-Based Solutions and Consulting | France | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 56.7 | 55.2 | 114 | 114.3 |
Southern Europe | Outcome-Based Solutions and Consulting | Italy | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 11.7 | 12.8 | 21.2 | 24.3 |
Southern Europe | Outcome-Based Solutions and Consulting | Other Southern Europe | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 83.2 | 76.6 | 163.3 | 154.3 |
Southern Europe | Permanent Recruitment | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 40.3 | 38.8 | 78.9 | 77.4 |
Southern Europe | Permanent Recruitment | France | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 13.6 | 14.5 | 28.1 | 29.4 |
Southern Europe | Permanent Recruitment | Italy | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 10.7 | 10.2 | 20.6 | 19.4 |
Southern Europe | Permanent Recruitment | Other Southern Europe | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 16 | 14.1 | 30.2 | 28.6 |
Southern Europe | Other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 12.5 | 16.1 | 27.7 | 30.9 |
Southern Europe | Other | France | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 4.2 | 6 | 9.3 | 11.4 |
Southern Europe | Other | Italy | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 6.4 | 6.1 | 12.9 | 12 |
Southern Europe | Other | Other Southern Europe | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1.9 | 4 | 5.5 | 7.5 |
Northern Europe | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1,183.2 | 1,393.2 | 2,372.9 | 2,810.8 |
Northern Europe | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1,149.9 | 1,354.8 | 2,306.5 | 2,734 |
Northern Europe | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 33.3 | 38.4 | 66.4 | 76.8 |
Northern Europe | Staffing and Interim | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1,050.8 | 1,234 | 2,104.2 | 2,489.2 |
Northern Europe | Outcome-Based Solutions and Consulting | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 86.5 | 106.1 | 176.2 | 215.9 |
Northern Europe | Permanent Recruitment | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 38.2 | 45 | 76.3 | 89.5 |
Northern Europe | Other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 7.7 | 8.1 | 16.2 | 16.2 |
APME | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 708.9 | 724.8 | 1,408.8 | 1,445 |
APME | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 675.7 | 689.5 | 1,347.1 | 1,378.4 |
APME | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 33.2 | 35.3 | 61.7 | 66.6 |
APME | Staffing and Interim | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 582 | 599.5 | 1,165.4 | 1,198.7 |
APME | Outcome-Based Solutions and Consulting | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 73.5 | 69 | 142.9 | 137.4 |
APME | Permanent Recruitment | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 50.1 | 52 | 93.8 | 101 |
APME | Other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 3.3 | 4.3 | 6.7 | 7.9 |
Right Management | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 50.4 | 52.4 | 96.2 | 102.4 |
Right Management | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 50.4 | 52.4 | 96.2 | 102.4 |
Right Management | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 0 | 0 | 0 | 0 |
Right Management | Staffing and Interim | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 0 | 0 | 0 | 0 |
Right Management | Outcome-Based Solutions and Consulting | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 12.3 | 12.5 | 22.4 | 24 |
Right Management | Permanent Recruitment | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 0 | 0 | 0 | 0 |
Right Management | Other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | $ 38.1 | $ 39.9 | $ 73.8 | $ 78.4 |