Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |
Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2019 | Sep. 30, 2018 |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | $ 5,248.9 | $ 5,418.7 | $ 15,666.9 | $ 16,598 |
Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 5,148.5 | 5,304.5 | 15,332.7 | 16,235.3 |
Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 100.4 | 114.2 | 334.2 | 362.7 |
Staffing and Interim | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 4,670.4 | 4,812.1 | 13,882.5 | 14,727.6 |
Outcome-Based Solutions and Consulting | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 360.2 | 372.4 | 1,088.3 | 1,130 |
Permanent Recruitment | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 137.6 | 152.4 | 445.6 | 479 |
Other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 80.7 | 81.8 | 250.5 | 261.4 |
Americas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1,070.7 | 1,040 | 3,121.4 | 3,115.1 |
Americas | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1,052.5 | 1,022.6 | 3,068.2 | 3,063.5 |
Americas | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 18.2 | 17.4 | 53.2 | 51.6 |
Americas | United States | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 645.7 | 633.2 | 1,880.2 | 1,890 |
Americas | United States | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 632.1 | 620.4 | 1,839.9 | 1,851.5 |
Americas | United States | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 13.6 | 12.8 | 40.3 | 38.5 |
Americas | Other Americas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 425 | 406.8 | 1,241.2 | 1,225.1 |
Americas | Other Americas | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 420.4 | 402.2 | 1,228.3 | 1,212 |
Americas | Other Americas | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 4.6 | 4.6 | 12.9 | 13.1 |
Americas | Staffing and Interim | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 969.1 | 944.2 | 2,827.3 | 2,827 |
Americas | Staffing and Interim | United States | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 564.5 | 556.1 | 1,644.5 | 1,658.4 |
Americas | Staffing and Interim | Other Americas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 404.6 | 388.1 | 1,182.8 | 1,168.6 |
Americas | Outcome-Based Solutions and Consulting | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 46 | 42.9 | 134.1 | 130.3 |
Americas | Outcome-Based Solutions and Consulting | United States | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 33.5 | 31.5 | 97.6 | 95.4 |
Americas | Outcome-Based Solutions and Consulting | Other Americas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 12.5 | 11.4 | 36.5 | 34.9 |
Americas | Permanent Recruitment | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 31.9 | 29.8 | 90.9 | 88.5 |
Americas | Permanent Recruitment | United States | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 25.2 | 23.7 | 72.2 | 69.9 |
Americas | Permanent Recruitment | Other Americas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 6.7 | 6.1 | 18.7 | 18.6 |
Americas | Other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 23.7 | 23.1 | 69.1 | 69.3 |
Americas | Other | United States | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 22.5 | 21.9 | 65.9 | 66.3 |
Americas | Other | Other Americas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1.2 | 1.2 | 3.2 | 3 |
Southern Europe | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 2,351.6 | 2,331.6 | 6,841 | 7,077.6 |
Southern Europe | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 2,320.2 | 2,301 | 6,738.9 | 6,976.1 |
Southern Europe | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 31.4 | 30.6 | 102.1 | 101.5 |
Southern Europe | France | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1,382.1 | 1,460.6 | 4,103.7 | 4,397.1 |
Southern Europe | France | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1,370.8 | 1,448.5 | 4,066 | 4,356.6 |
Southern Europe | France | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 11.3 | 12.1 | 37.7 | 40.5 |
Southern Europe | Italy | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 376.6 | 410.2 | 1,126.5 | 1,266.8 |
Southern Europe | Italy | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 369.3 | 402.8 | 1,100 | 1,241.2 |
Southern Europe | Italy | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 7.3 | 7.4 | 26.5 | 25.6 |
Southern Europe | Other Southern Europe | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 592.9 | 460.8 | 1,610.8 | 1,413.7 |
Southern Europe | Other Southern Europe | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 580.1 | 449.7 | 1,572.9 | 1,378.3 |
Southern Europe | Other Southern Europe | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 12.8 | 11.1 | 37.9 | 35.4 |
Southern Europe | Staffing and Interim | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 2,158.8 | 2,146.7 | 6,243.1 | 6,491.5 |
Southern Europe | Staffing and Interim | France | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1,309.8 | 1,390 | 3,880 | 4,171.4 |
Southern Europe | Staffing and Interim | Italy | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 354.9 | 386.5 | 1,050.1 | 1,187.4 |
Southern Europe | Staffing and Interim | Other Southern Europe | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 494.1 | 370.2 | 1,313 | 1,132.7 |
Southern Europe | Outcome-Based Solutions and Consulting | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 148.8 | 137.6 | 447.3 | 430.5 |
Southern Europe | Outcome-Based Solutions and Consulting | France | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 56.6 | 53.3 | 170.6 | 167.6 |
Southern Europe | Outcome-Based Solutions and Consulting | Italy | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 10.2 | 11.5 | 31.4 | 35.8 |
Southern Europe | Outcome-Based Solutions and Consulting | Other Southern Europe | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 82 | 72.8 | 245.3 | 227.1 |
Southern Europe | Permanent Recruitment | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 35.6 | 34.2 | 114.5 | 111.6 |
Southern Europe | Permanent Recruitment | France | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 12.1 | 12.7 | 40.2 | 42.1 |
Southern Europe | Permanent Recruitment | Italy | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 8.1 | 8 | 28.7 | 27.4 |
Southern Europe | Permanent Recruitment | Other Southern Europe | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 15.4 | 13.5 | 45.6 | 42.1 |
Southern Europe | Other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 8.4 | 13.1 | 36.1 | 44 |
Southern Europe | Other | France | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 3.6 | 4.6 | 12.9 | 16 |
Southern Europe | Other | Italy | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 3.4 | 4.2 | 16.3 | 16.2 |
Southern Europe | Other | Other Southern Europe | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1.4 | 4.3 | 6.9 | 11.8 |
Northern Europe | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1,156.6 | 1,287.1 | 3,529.5 | 4,097.9 |
Northern Europe | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1,127.4 | 1,255.9 | 3,433.9 | 3,989.9 |
Northern Europe | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 29.2 | 31.2 | 95.6 | 108 |
Northern Europe | Staffing and Interim | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 1,037.2 | 1,138.8 | 3,141.4 | 3,628 |
Northern Europe | Outcome-Based Solutions and Consulting | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 78 | 104.3 | 254.2 | 320.2 |
Northern Europe | Permanent Recruitment | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 33.6 | 36.6 | 109.9 | 126.1 |
Northern Europe | Other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 7.8 | 7.4 | 24 | 23.6 |
APME | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 621.9 | 713 | 2,030.7 | 2,158 |
APME | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 600.3 | 678 | 1,947.4 | 2,056.4 |
APME | Services transferred at a point in time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 21.6 | 35 | 83.3 | 101.6 |
APME | Staffing and Interim | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 505.3 | 582.4 | 1,670.7 | 1,781.1 |
APME | Outcome-Based Solutions and Consulting | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 76.6 | 75.4 | 219.5 | 212.8 |
APME | Permanent Recruitment | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 36.5 | 51.8 | 130.3 | 152.8 |
APME | Other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 3.5 | 3.4 | 10.2 | 11.3 |
Right Management | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 48.1 | 47 | 144.3 | 149.4 |
Right Management | Services transferred over time | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 48.1 | 47 | 144.3 | 149.4 |
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 | 10.8 | 12.2 | 33.2 | 36.2 |
Right Management | Permanent Recruitment | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | 0 | 0 | 0 | 0 |
Right Management | Other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue | $ 37.3 | $ 34.8 | $ 111.1 | $ 113.2 |