Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Cumulative foreign currency translation	$ (170.1)	$ (104.1)
Unrecognized pension costs (net of tax benefit of $25.5 in 2018 and $30.7 in 2017)	(69.7)	(86.5)
Unrealized gain (loss) on cash flow hedges (net of tax expense of $0.3 in 2018 and $0.7 in 2017)	6.1	4.5
Total accumulated other comprehensive income (loss)	(233.7)	(186.1)
Unrecognized pension costs, tax benefit	25.5	30.7
Unrealized gain (loss) on cash flow hedges, tax expense	0.3	0.7
Foreign currency translation adjustment [Abstract]
Foreign currency translation adjustment, pre-tax amount	(67.9)	44.7	$ (40.2)
Foreign currency translation adjustment, tax (expense) benefit	0.0	0.0	0.0
Foreign currency translation adjustments, net-of-tax amount	(67.9)	44.7	(40.2)
Pension plans [Abstract]
Net actuarial gains (losses) and prior service costs arising during the period, pre-tax amount	9.6	(17.6)	(12.5)
Net actuarial gains (losses) and prior service costs arising during the period, tax (expense) benefit	(1.8)	4.4	4.1
Net actuarial gains (losses) and prior service costs arising during the period, net-of-tax amount	7.8	(13.2)	(8.4)
Amortization of net actuarial (gains) losses and prior service costs, pre-tax amount	12.1	7.6	8.0
Amortization of net actuarial (gains) losses and prior service costs, tax (expense) benefit	(3.0)	(2.9)	(2.8)
Amortization of net actuarial (gains) losses and prior service costs, net-of-tax amount	9.1	4.7	5.2
Unrealized gains (losses) on cash flow hedges [Abstract]
Unrealized gains (losses) on cash flow hedges, pre-tax amount	1.5	0.2	2.4
Unrealized gains (losses) on cash flow hedges, tax (expense) benefit	0.1	0.1	(0.8)
Unrealized gains (losses) on cash flow hedges, net-of-tax amount	1.6	0.3	1.6
Total other comprehensive income (loss), pre-tax amount	(44.7)	34.9	(42.3)
Total other comprehensive income (loss)	(4.7)	1.6	0.5
Total other comprehensive income (loss), net of tax	$ (49.4)	$ 36.5	$ (41.8)