Retirement Benefits - Obligations and Funded Status (Details) - USD ($) $ in Millions | Oct. 08, 2019 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 |
Total | | | | |
Changes in the benefit obligation [Roll Forward] | | | | |
Benefit obligation at beginning of year | | $ 1,066.1 | $ 1,191.8 | |
Service cost | | 9.9 | 10.5 | $ 11.3 |
Interest cost | | 44.5 | 43.7 | 50.3 |
Participant contributions | | 0.1 | 0.3 | |
Plan amendments | | (0.6) | 0 | |
Plan combinations | | 1.4 | 0.7 | |
Curtailment | | (0.8) | 0 | |
Settlements | | (54.5) | 0 | |
Benefits paid | | (67.3) | (66.1) | |
Divestitures(a) | | 0 | (3.9) | |
Actuarial (gains) losses | | 136.7 | (88.7) | |
Foreign currency exchange effects | | 9.7 | (22.2) | |
Benefit obligation at end of year | | 1,145.2 | 1,066.1 | 1,191.8 |
Changes in plan assets [Roll Forward] | | | | |
Fair value of plan assets at beginning of year | | 867.2 | 980.1 | |
Return on assets – actual | | 143.3 | (51.2) | |
Participant contributions | | 0.1 | 0.3 | |
Employer contributions | | 14.6 | 17.4 | |
Plan combinations | | 1.4 | 0.7 | |
Settlements | | (53.9) | 0 | |
Benefits paid | | (67.3) | (66.1) | |
Foreign currency exchange effects | | 9 | (14) | |
Fair value of plan assets at end of year | | 914.4 | 867.2 | 980.1 |
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract] | | | | |
Funded status | | (230.8) | (198.9) | |
Current liability, included in accrued liabilities | | 1.9 | 2 | |
Noncurrent liability | | 228.9 | 196.9 | |
Net pension liability | | 230.8 | 198.9 | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Beginning of year - net gains and losses | | (368) | (391.8) | |
Net actuarial gains (losses) arising during the year | | (53) | (27.2) | |
Reclassification adjustment for amortization of prior actuarial losses included in net income (loss) | | 45.2 | 46.4 | |
Foreign currency exchange effects | | (2.3) | 4.6 | |
End of year - net gains and losses | | (378.1) | (368) | (391.8) |
Benefit plan prior service cost recognized in accumulated other comprehensive income (loss): | | | | |
Beginning of year - net prior service (cost) credit | | (1.2) | (8.3) | |
Prior service credit (cost) from plan amendments during the year | | 0.6 | 0 | |
Reclassification adjustment for amortization of prior service cost included in net income (loss) | | 0.1 | 7.1 | |
Foreign currency exchange effects | | 0 | 0 | |
End of year - net prior service (cost) credit | | (0.5) | (1.2) | (8.3) |
Retirement benefits other than pension | | | | |
Changes in the benefit obligation [Roll Forward] | | | | |
Benefit obligation at beginning of year | | 555.6 | 589.3 | |
Service cost | | 0.2 | 0.2 | 0.1 |
Interest cost | | 21.1 | 20.3 | 21.6 |
Plan amendments | | (0.3) | 0 | |
Acquisition | | 0.9 | 0.2 | |
Curtailment | | (0.2) | 0 | |
Benefits paid | | (37.8) | (36.8) | |
Actuarial (gains) losses | | (2.6) | (16.5) | |
Foreign currency exchange effects | | (0.2) | (1.1) | |
Benefit obligation at end of year | | 536.7 | 555.6 | 589.3 |
Changes in plan assets [Roll Forward] | | | | |
Fair value of plan assets at beginning of year | | 181.7 | 219.2 | |
Return on assets – actual | | 25.9 | (7.6) | |
Employer contributions | | 8.5 | 8.2 | |
Net transfers to (from) plan assets | | (0.4) | (1.3) | |
Benefits paid | | (37.8) | (36.8) | |
Fair value of plan assets at end of year | | 177.9 | 181.7 | 219.2 |
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract] | | | | |
Funded status | | (358.8) | (373.9) | |
Current liability, included in accrued liabilities | | 11 | 7.8 | |
Noncurrent liability | | 347.8 | 366.1 | |
Net pension liability | | 358.8 | 373.9 | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Beginning of year - net gains and losses | | (333.8) | (352.8) | |
Net actuarial gains (losses) arising during the year | | 15.2 | (7.8) | |
Reclassification adjustment for amortization of prior actuarial losses included in net income (loss) | | 21.2 | 26.1 | |
Foreign currency exchange effects | | 0.1 | 0.7 | |
End of year - net gains and losses | | (297.3) | (333.8) | (352.8) |
Benefit plan prior service cost recognized in accumulated other comprehensive income (loss): | | | | |
Beginning of year - net prior service (cost) credit | | 34.2 | 38 | |
Prior service credit (cost) from plan amendments during the year | | 0.3 | 0 | |
Reclassification adjustment for amortization of prior service cost included in net income (loss) | | (5.1) | (3.5) | |
Foreign currency exchange effects | | 0 | (0.3) | |
End of year - net prior service (cost) credit | | 29.4 | 34.2 | 38 |
U.S. Plans | | | | |
Changes in the benefit obligation [Roll Forward] | | | | |
Benefit obligation at beginning of year | | 801.9 | 890.3 | |
Service cost | | 0 | 0 | 0 |
Interest cost | | 34.1 | 31.9 | 35.1 |
Participant contributions | | 0 | 0 | |
Plan amendments | | 0 | 0 | |
Plan combinations | | 0 | 0 | |
Settlements | | (53.6) | 0 | |
Benefits paid | | (49.1) | (49.3) | |
Actuarial (gains) losses | | 93.5 | (71) | |
Foreign currency exchange effects | | 0 | 0 | |
Benefit obligation at end of year | | 826.8 | 801.9 | 890.3 |
Changes in plan assets [Roll Forward] | | | | |
Fair value of plan assets at beginning of year | | 686.6 | 777.2 | |
Return on assets – actual | | 114.1 | (42.2) | |
Participant contributions | | 0 | 0 | |
Employer contributions | | 0.7 | 0.9 | |
Plan combinations | | 0 | 0 | |
Settlements | | (53) | 0 | |
Benefits paid | | (49.1) | (49.3) | |
Foreign currency exchange effects | | 0 | 0 | |
Fair value of plan assets at end of year | | 699.3 | 686.6 | 777.2 |
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract] | | | | |
Funded status | | (127.5) | (115.3) | |
Current liability, included in accrued liabilities | | 0.6 | 1.2 | |
Noncurrent liability | | 126.9 | 114.1 | |
Net pension liability | | 127.5 | 115.3 | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Beginning of year - net gains and losses | | (306) | (308.9) | |
Net actuarial gains (losses) arising during the year | | (29.5) | (24.8) | |
Reclassification adjustment for amortization of prior actuarial losses included in net income (loss) | | 38.9 | 27.7 | |
Foreign currency exchange effects | | 0 | 0 | |
End of year - net gains and losses | | (296.6) | (306) | (308.9) |
Benefit plan prior service cost recognized in accumulated other comprehensive income (loss): | | | | |
Beginning of year - net prior service (cost) credit | | 0 | 0 | |
Prior service credit (cost) from plan amendments during the year | | 0 | 0 | |
Reclassification adjustment for amortization of prior service cost included in net income (loss) | | 0 | 0 | |
Foreign currency exchange effects | | 0 | 0 | |
End of year - net prior service (cost) credit | | 0 | 0 | 0 |
U.S. Plans | Actuarial Gains (Losses) - Asset Return Different from Expected | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | 63 | | |
U.S. Plans | Actuarial Gains (Losses) - Change in Discount Rate | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | (96) | | |
U.S. Plans | Actuarial Gains (Losses) - Change of Mortality Tables | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | 5 | | |
U.S. Plans | Total | | | | |
Changes in the benefit obligation [Roll Forward] | | | | |
Settlements | $ (54) | | | |
Non-U.S. Plans | | | | |
Changes in the benefit obligation [Roll Forward] | | | | |
Benefit obligation at beginning of year | | 264.2 | 301.5 | |
Service cost | | 9.9 | 10.5 | 11.3 |
Interest cost | | 10.4 | 11.8 | 15.2 |
Participant contributions | | 0.1 | 0.3 | |
Plan amendments | | (0.6) | 0 | |
Plan combinations | | 1.4 | 0.7 | |
Curtailment | | (0.8) | | |
Settlements | | (0.9) | 0 | |
Benefits paid | | (18.2) | (16.8) | |
Divestitures(a) | | 0 | (3.9) | |
Actuarial (gains) losses | | 43.2 | (17.7) | |
Foreign currency exchange effects | | 9.7 | (22.2) | |
Benefit obligation at end of year | | 318.4 | 264.2 | 301.5 |
Changes in plan assets [Roll Forward] | | | | |
Fair value of plan assets at beginning of year | | 180.6 | 202.9 | |
Return on assets – actual | | 29.2 | (9) | |
Participant contributions | | 0.1 | 0.3 | |
Employer contributions | | 13.9 | 16.5 | |
Plan combinations | | 1.4 | 0.7 | |
Settlements | | (0.9) | 0 | |
Benefits paid | | (18.2) | (16.8) | |
Foreign currency exchange effects | | 9 | (14) | |
Fair value of plan assets at end of year | | 215.1 | 180.6 | 202.9 |
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract] | | | | |
Funded status | | (103.3) | (83.6) | |
Current liability, included in accrued liabilities | | 1.3 | 0.8 | |
Noncurrent liability | | 102 | 82.8 | |
Net pension liability | | 103.3 | 83.6 | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Beginning of year - net gains and losses | | (62) | (82.9) | |
Net actuarial gains (losses) arising during the year | | (23.5) | (2.4) | |
Reclassification adjustment for amortization of prior actuarial losses included in net income (loss) | | 6.3 | 18.7 | |
Foreign currency exchange effects | | (2.3) | 4.6 | |
End of year - net gains and losses | | (81.5) | (62) | (82.9) |
Benefit plan prior service cost recognized in accumulated other comprehensive income (loss): | | | | |
Beginning of year - net prior service (cost) credit | | (1.2) | (8.3) | |
Prior service credit (cost) from plan amendments during the year | | 0.6 | 0 | |
Reclassification adjustment for amortization of prior service cost included in net income (loss) | | 0.1 | 7.1 | |
Foreign currency exchange effects | | 0 | 0 | |
End of year - net prior service (cost) credit | | (0.5) | (1.2) | (8.3) |
Non-U.S. Plans | Actuarial Gains (Losses) - Asset Return Different from Expected | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | 19 | | |
Non-U.S. Plans | Actuarial Gains (Losses) - Change in Discount Rate | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | 37 | | |
UMWA Plans | | | | |
Changes in the benefit obligation [Roll Forward] | | | | |
Benefit obligation at beginning of year | | 479.1 | 513.5 | |
Service cost | | 0 | 0 | 0 |
Interest cost | | 17.3 | 17.1 | 18.4 |
Plan amendments | | 0 | 0 | |
Curtailment | | 0 | 0 | |
Benefits paid | | (29.3) | (28.6) | |
Actuarial (gains) losses | | (42.5) | (22.9) | |
Foreign currency exchange effects | | 0 | 0 | |
Benefit obligation at end of year | | 424.6 | 479.1 | 513.5 |
Changes in plan assets [Roll Forward] | | | | |
Fair value of plan assets at beginning of year | | 181.7 | 219.2 | |
Return on assets – actual | | 25.9 | (7.6) | |
Net transfers to (from) plan assets | | (0.4) | (1.3) | |
Benefits paid | | (29.3) | (28.6) | |
Fair value of plan assets at end of year | | 177.9 | 181.7 | 219.2 |
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract] | | | | |
Funded status | | (246.7) | (297.4) | |
Current liability, included in accrued liabilities | | 0 | 0 | |
Noncurrent liability | | 246.7 | 297.4 | |
Net pension liability | | 246.7 | 297.4 | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Beginning of year - net gains and losses | | (290.9) | (309.8) | |
Net actuarial gains (losses) arising during the year | | 55.1 | | |
Reclassification adjustment for amortization of prior actuarial losses included in net income (loss) | | 16.6 | 20.3 | |
Foreign currency exchange effects | | 0 | 0 | |
End of year - net gains and losses | | (219.2) | (290.9) | (309.8) |
Benefit plan prior service cost recognized in accumulated other comprehensive income (loss): | | | | |
Beginning of year - net prior service (cost) credit | | 32.7 | 37.3 | |
Prior service credit (cost) from plan amendments during the year | | 0 | 0 | |
Reclassification adjustment for amortization of prior service cost included in net income (loss) | | (4.7) | (4.6) | |
Foreign currency exchange effects | | 0 | 0 | |
End of year - net prior service (cost) credit | | 28 | 32.7 | 37.3 |
UMWA Plans | Actuarial Gains (Losses) - Asset Return Different from Expected | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | 13 | | |
UMWA Plans | Actuarial Gains (Losses) - Change in Discount Rate | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | (50) | | |
UMWA Plans | Actuarial Gains (Losses) - Change of Mortality Tables | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | 6 | | |
UMWA Plans | Actuarial Gains (Losses) - Change in Census Data | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | 4 | | |
UMWA Plans | Actuarial Gains (Losses) - Change in Claims Experience | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | 53 | | |
UMWA Plans | Actuarial Gains (Losses) - Excise Tax Update | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | 29 | | |
Black Lung and Other Plans | | | | |
Changes in the benefit obligation [Roll Forward] | | | | |
Benefit obligation at beginning of year | | 76.5 | 75.8 | |
Service cost | | 0.2 | 0.2 | 0.1 |
Interest cost | | 3.8 | 3.2 | 3.2 |
Plan amendments | | (0.3) | 0 | |
Acquisition | | 0.9 | 0.2 | |
Curtailment | | (0.2) | 0 | |
Benefits paid | | (8.5) | (8.2) | |
Actuarial (gains) losses | | 39.9 | 6.4 | |
Foreign currency exchange effects | | (0.2) | (1.1) | |
Benefit obligation at end of year | | 112.1 | 76.5 | 75.8 |
Changes in plan assets [Roll Forward] | | | | |
Fair value of plan assets at beginning of year | | 0 | 0 | |
Return on assets – actual | | 0 | 0 | |
Employer contributions | | 8.5 | 8.2 | |
Benefits paid | | (8.5) | (8.2) | |
Fair value of plan assets at end of year | | 0 | 0 | 0 |
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract] | | | | |
Funded status | | (112.1) | (76.5) | |
Current liability, included in accrued liabilities | | 11 | 7.8 | |
Noncurrent liability | | 101.1 | 68.7 | |
Net pension liability | | 112.1 | 76.5 | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Beginning of year - net gains and losses | | (42.9) | (43) | |
Net actuarial gains (losses) arising during the year | | (39.9) | | |
Reclassification adjustment for amortization of prior actuarial losses included in net income (loss) | | 4.6 | 5.8 | |
Foreign currency exchange effects | | 0.1 | 0.7 | |
End of year - net gains and losses | | (78.1) | (42.9) | (43) |
Benefit plan prior service cost recognized in accumulated other comprehensive income (loss): | | | | |
Beginning of year - net prior service (cost) credit | | 1.5 | 0.7 | |
Prior service credit (cost) from plan amendments during the year | | 0.3 | 0 | |
Reclassification adjustment for amortization of prior service cost included in net income (loss) | | (0.4) | 1.1 | |
Foreign currency exchange effects | | 0 | (0.3) | |
End of year - net prior service (cost) credit | | 1.4 | 1.5 | $ 0.7 |
Black Lung and Other Plans | Actuarial Gains (Losses) - Change in Discount Rate | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | (5) | | |
Black Lung and Other Plans | Actuarial Gains (Losses) - Change of Mortality Tables | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | 3 | | |
Black Lung and Other Plans | Actuarial Gains (Losses) - Change in Census Data | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | (8) | | |
Black Lung and Other Plans | Actuarial Gains (Losses) - Claims Assumptions Updates | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | $ (27) | | |
ASU 2017-07 | U.S. Plans | Actuarial Gains (Losses) - Asset Return Different from Expected | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | | (96) | |
ASU 2017-07 | U.S. Plans | Actuarial Gains (Losses) - Change in Discount Rate | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | | 65 | |
ASU 2017-07 | U.S. Plans | Actuarial Gains (Losses) - Change of Mortality Tables | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | | 4 | |
ASU 2017-07 | UMWA Plans | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | | (1.4) | |
ASU 2017-07 | UMWA Plans | Actuarial Gains (Losses) - Asset Return Different from Expected | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | | (24) | |
ASU 2017-07 | UMWA Plans | Actuarial Gains (Losses) - Change in Discount Rate | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | | 33 | |
ASU 2017-07 | UMWA Plans | Actuarial Gains (Losses) - Change of Mortality Tables | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | | (32) | |
ASU 2017-07 | UMWA Plans | Actuarial Gains (Losses) - Claims Assumptions Updates | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | | 16 | |
ASU 2017-07 | Black Lung and Other Plans | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | | (6.4) | |
ASU 2017-07 | Black Lung and Other Plans | Actuarial Gains (Losses) - Change in Discount Rate | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | | 4 | |
ASU 2017-07 | Black Lung and Other Plans | Actuarial Gains (Losses) - Change in Census Data | | | | |
Benefit plan net actuarial losses recognized in accumulated other comprehensive income (loss): | | | | |
Net actuarial gains (losses) arising during the year | | | $ (9) | |