Pension and Other Post Retirement Benefits (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) $ / hour	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Defined Benefit Plan Disclosure [Line Items]
IAM Level of Contribution per hour until June 2019 | $ / hour	1.75
Amounts recognized in balance sheet
Noncurrent assets	$ 449.1	$ 326.7
Noncurrent liabilities	(35.7)	(34.6)
UNITED STATES
Change in fair value of plan assets:
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant	0.0	0.0
Other Benefits [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	0.0	0.0
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning balance	40.3	47.2
Service cost	0.9	1.1
Interest cost	1.2	1.0
Actuarial loss (gain)	(1.8)	2.4
Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits	3.9	0.0
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment	0.0	0.0
Defined Benefit Plan, Benefit Obligation, Benefits Paid	7.2	7.6
Projected benefit obligation at the end of the period	41.8	40.3	$ 47.2
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant	$ 0.9	$ 1.0
Total recognized in other net periodic benefit and OCI (income) loss
Discount rate	2.55%	3.74%
Medical Assumptions:
Trend assumed for the year	5.90%	6.24%
Ultimate trend rate	4.50%	4.50%
Year that ultimate trend rate is reached	2038	2038
Change in fair value of plan assets:
Beginning balance	$ 0.0	$ 0.0
Company contributions	6.3	6.6
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant	0.9	1.0
Defined Benefit Plan, Plan Assets, Administration Expense	0.0	0.0
Defined Benefit Plan, Plan Assets, Benefits Paid	7.2	7.6
Ending balance	0.0	0.0	0.0
Reconciliation of funded status to net amounts recognized:
Funded status (deficit)	(41.8)	(40.3)
Net amounts recognized	(41.8)	(40.3)
Amounts recognized in balance sheet
Noncurrent assets	0.0	0.0
Current liabilities	(7.3)	(6.9)
Noncurrent liabilities	(34.5)	(33.4)
Net amounts recognized	(41.8)	(40.3)
Amounts not yet reflected in net periodic benefit cost and included in AOCI:
Accumulated gain (loss)	22.6	27.5
Accumulated other comprehensive income (AOCI)	22.6	27.5
Cumulative employer contributions in excess of net periodic benefit cost	(64.4)	(67.8)
Net amount recognized in the balance sheet	(41.8)	(40.3)
Information for pension plans with benefit obligations in excess of plan assets:
Projected benefit obligation	41.8	40.3
Accumulated benefit obligation	0.0	0.0
Pension Plan [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	299.7	(77.1)
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning balance	997.0	1,084.4
Service cost	0.0	0.0
Interest cost	36.5	34.7
Actuarial loss (gain)	(141.1)	91.7
Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits	5.2	0.0
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment	(49.9)	0.0
Defined Benefit Plan, Benefit Obligation, Benefits Paid	33.3	30.4
Projected benefit obligation at the end of the period	1,096.6	997.0	1,084.4
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant	$ 0.0	$ 0.0
Total recognized in other net periodic benefit and OCI (income) loss
Discount rate	3.19%	4.21%
Change in fair value of plan assets:
Beginning balance	$ 1,302.8	$ 1,410.3
Company contributions	0.1	0.1
Defined Benefit Plan, Plan Assets, Administration Expense	0.0	0.0
Defined Benefit Plan, Plan Assets, Benefits Paid	33.2	30.5
Ending balance	1,519.5	1,302.8	1,410.3
Reconciliation of funded status to net amounts recognized:
Funded status (deficit)	422.9	305.8
Net amounts recognized	422.9	305.8
Amounts recognized in balance sheet
Noncurrent assets	424.2	307.0
Current liabilities	(0.1)	0.0
Noncurrent liabilities	(1.2)	(1.2)
Net amounts recognized	422.9	305.8
Amounts not yet reflected in net periodic benefit cost and included in AOCI:
Accumulated gain (loss)	(46.0)	(141.9)
Accumulated other comprehensive income (AOCI)	(46.0)	(141.9)
Cumulative employer contributions in excess of net periodic benefit cost	468.9	447.7
Net amount recognized in the balance sheet	422.9	305.8
Information for pension plans with benefit obligations in excess of plan assets:
Projected benefit obligation	1.3	1.2
Accumulated benefit obligation	1.3	1.2
Pension Plan [Member] | UNITED KINGDOM
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	11.1	(3.0)
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment	(2.1)	(7.5)
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning balance	59.9	76.9
Service cost	0.9	1.3
Interest cost	1.6	1.7
Actuarial loss (gain)	(5.5)	6.9
Defined Benefit Plan, Benefit Obligation, Benefits Paid	0.8	0.6
Expense paid	(0.9)	(1.3)
Exchange rate changes	2.6	(3.7)
Projected benefit obligation at the end of the period	$ 66.7	$ 59.9	76.9
Total recognized in other net periodic benefit and OCI (income) loss
Discount rate	2.10%	3.00%
Salary increases	3.15%	3.40%
Change in fair value of plan assets:
Beginning balance	$ 79.6	$ 96.8
Company contributions	1.7	1.7
Expense paid	(0.9)	(1.3)
Defined Benefit Plan, Plan Assets, Administration Expense	(0.9)	(1.3)
Exchange rate changes	3.5	(4.9)
Defined Benefit Plan, Plan Assets, Payment for Settlement	(2.6)	(9.1)
Defined Benefit Plan, Plan Assets, Benefits Paid	0.8	0.6
Ending balance	91.6	79.6	96.8
Reconciliation of funded status to net amounts recognized:
Funded status (deficit)	24.9	19.7
Net amounts recognized	24.9	19.7
Amounts recognized in balance sheet
Noncurrent assets	24.9	19.7
Net amounts recognized	24.9	19.7
Amounts not yet reflected in net periodic benefit cost and included in AOCI:
Accumulated gain (loss)	5.9	3.1
Accumulated other comprehensive income (AOCI)	5.9	3.1
Prepaid pension cost	19.0	16.6
Net amount recognized in the balance sheet	24.9	19.7
Annual Expense [Member] | Other Benefits [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Amortization of Gain (Loss)	(2.2)	(2.3)	(2.2)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	7.8	0.2	(3.5)
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Service cost	0.9	1.1	1.2
Interest cost	1.2	1.1	1.2
Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits	$ (3.9)	$ 0.0	$ 0.0
Total recognized in other net periodic benefit and OCI (income) loss
Discount rate	3.74%	3.03%	3.21%
Medical Assumptions:
Trend assumed for the year	6.24%	6.59%	6.93%
Ultimate trend rate	4.50%	4.50%	4.50%
Year that ultimate trend rate is reached	2038	2038	2038
Amounts not yet reflected in net periodic benefit cost and included in AOCI:
Accumulated gain (loss)	$ 4.9	$ 0.8	$ 4.2
Accumulated other comprehensive income (AOCI)	4.9	0.8	4.2
Annual Expense [Member] | Pension Plan [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Amortization of Gain (Loss)	0.5	0.0	0.0
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	(117.0)	(20.1)	58.9
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Service cost	0.0	0.0	0.0
Interest cost	36.5	34.7	35.7
Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits	$ (5.2)	$ 0.0	$ 0.0
Total recognized in other net periodic benefit and OCI (income) loss
Discount rate	4.21%	3.59%	4.15%
Amounts not yet reflected in net periodic benefit cost and included in AOCI:
Accumulated gain (loss)	$ (95.9)	$ 52.3	$ (24.8)
Accumulated other comprehensive income (AOCI)	(95.9)	52.3	(24.8)
Annual Expense [Member] | Pension Plan [Member] | UNITED KINGDOM
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	(0.2)	(0.4)	(0.3)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	(3.2)	0.7	6.6
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Service cost	0.9	1.3	1.3
Interest cost	$ 1.7	$ 1.7	$ 2.0
Total recognized in other net periodic benefit and OCI (income) loss
Discount rate	3.00%	2.60%	2.70%
Salary increases	3.40%	3.35%	3.20%
Amounts not yet reflected in net periodic benefit cost and included in AOCI:
Accumulated gain (loss)	$ (3.2)	$ (0.5)	$ (6.7)
Accumulated other comprehensive income (AOCI)	$ (3.2)	$ (0.5)	$ (6.7)