Equity - Schedule of components of other comprehensive income (loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Foreign currency translation				$ (121.4)	$ (29.2)
Derivative instrument fair market value, net of income taxes of $(2.2) and $(3.2)				(3.8)	(6.3)
Employee pension and postretirement benefit adjustments, net of income taxes of $(35.2) and $(40.1)				(82.6)	(95.0)
Accumulated other comprehensive income (loss), net of tax, beginning balance	$ (130.5)	$ (6.9)	$ (6.9)	(207.8)	(130.5)
Derivative instrument fair market value, tax				(2.2)	(3.2)
Employee pension and postretirement benefit adjustments, tax				(35.2)	(40.1)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(130.5)	(6.9)
Other comprehensive loss before reclassifications	(60.3)	(129.3)
Amounts reclassified from accumulated other comprehensive income	(17.0)	5.7
Net current period other comprehensive income	(77.3)	(123.6)	22.5
Accumulated other comprehensive income (loss), net of tax, ending balance	(207.8)	(130.5)	(6.9)
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(6.3)	1.0	1.0	(3.8)	(6.3)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(6.3)	1.0
Other comprehensive loss before reclassifications	14.0	(9.9)
Amounts reclassified from accumulated other comprehensive income	(11.5)	2.6
Net current period other comprehensive income	2.5	(7.3)
Accumulated other comprehensive income (loss), net of tax, ending balance	(3.8)	(6.3)	1.0
Pension & Postretirement
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(95.0)	(62.7)	(62.7)	(82.6)	(95.0)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(95.0)	(62.7)
Other comprehensive loss before reclassifications	17.9	(35.4)
Amounts reclassified from accumulated other comprehensive income	(5.5)	3.1
Net current period other comprehensive income	12.4	(32.3)
Accumulated other comprehensive income (loss), net of tax, ending balance	(82.6)	(95.0)	(62.7)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(29.2)	54.8	54.8	$ (121.4)	$ (29.2)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(29.2)	54.8
Other comprehensive loss before reclassifications	(92.2)	(84.0)
Amounts reclassified from accumulated other comprehensive income	0.0	0.0
Net current period other comprehensive income	(92.2)	(84.0)
Accumulated other comprehensive income (loss), net of tax, ending balance	$ (121.4)	$ (29.2)	$ 54.8