Accumulated Other Comprehensive Loss - Changes in accumulated other comprehensive loss - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, Current Period, Tax	$ (2.2)	$ (2.6)	$ (5.2)
Before-tax reclassification of net actuarial gains/(losses)	(4.9)	(5.1)	(5.0)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	4,311.1	4,048.7	3,397.4
Other comprehensive income (loss), net of tax, before reclassifications	4.0	(2.8)	(12.7)
Amounts reclassified from accumulated other comprehensive loss, net of tax	7.3	7.8	12.2
Less: noncontrolling interest	(11.3)	(5.0)	0.5
Other comprehensive income	8.7	1.9	(3.5)
Ending balance	4,858.0	4,311.1	4,048.7
Cost of sales
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before-tax reclassification of net actuarial gains/(losses)	3.7	4.1	4.2
Currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, Current Period, Tax	0.0	0.0	0.0
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(23.7)	(24.5)	(18.5)
Other comprehensive income (loss), net of tax, before reclassifications	1.3	0.8	(6.0)
Amounts reclassified from accumulated other comprehensive loss, net of tax	0.0	0.0	0.0
Other comprehensive income	1.3	0.8	(6.0)
Ending balance	(22.4)	(23.7)	(24.5)
Currency translation adjustments attributable to noncontrolling interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Less: noncontrolling interest	0.0	0.0	0.0
Unrealized loss on derivative financial instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, Current Period, Tax	(0.7)	(0.7)	(3.4)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(0.1)	(1.3)	(6.6)
Other comprehensive income (loss), net of tax, before reclassifications	(0.9)	(0.3)	(0.7)
Amounts reclassified from accumulated other comprehensive loss, net of tax	3.9	4.6	9.0
Other comprehensive income	0.4	1.2	5.3
Ending balance	0.3	(0.1)	(1.3)
Unrealized loss on derivative financial instruments attributable to noncontrolling interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Less: noncontrolling interest	(2.6)	(3.1)	(3.0)
Net actuarial gains/(losses) of defined benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, Current Period, Tax	(1.5)	(1.9)	(1.8)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(89.7)	(89.6)	(86.8)
Other comprehensive income (loss), net of tax, before reclassifications	3.6	(3.3)	(6.0)
Amounts reclassified from accumulated other comprehensive loss, net of tax	3.4	3.2	3.2
Other comprehensive income	7.0	(0.1)	(2.8)
Ending balance	(82.7)	(89.7)	(89.6)
Net actuarial gains/(losses) of defined benefit plans attributable to noncontrolling interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Less: noncontrolling interest	0.0	0.0	0.0
Accumulated Other Comprehensive Loss
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(113.5)	(115.4)	(111.9)
Less: noncontrolling interest	(8.7)	(1.9)	3.5
Ending balance	(104.8)	(113.5)	(115.4)
Accumulated Other Comprehensive Loss attributable to noncontrolling interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	392.6	394.8	401.5
Less: noncontrolling interest	(2.6)	(3.1)	(3.0)
Ending balance	$ 356.9	$ 392.6	$ 394.8