Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Other Comprehensive Income (Loss), before Tax
Other Comprehensive Income (Loss), before Tax	$ 1.8	$ 0.2	$ 4.6	$ 108.6
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosures [Abstract]
Other Comprehensive Income (Loss), Tax	(0.7)	(0.1)	(1.7)	(41.2)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Other Comprehensive Income (Loss), Net of Tax	1.1	0.1	2.9	67.4
Accumulated Defined Benefit Plans Adjustment Attributable to Parent
Other Comprehensive Income (Loss), before Tax
Other Comprehensive Income (Loss), before Tax	1.1	1.0	3.3	109.6
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosures [Abstract]
Other Comprehensive Income (Loss), Tax	(0.4)	(0.3)	(1.2)	(41.5)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Other Comprehensive Income (Loss), Net of Tax	0.7	0.7	2.1	68.1
Amortization of net actuarial loss
Other Comprehensive Income (Loss), before Tax
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0.1	0.3	0.3	0.8
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosures [Abstract]
Reclassification from AOCI, Current Period, Tax	0.0	(0.1)	(0.1)	(0.3)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0.1	0.2	0.2	0.5
Amortization of prior service cost
Other Comprehensive Income (Loss), before Tax
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	1.0	0.7	3.0	2.2
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosures [Abstract]
Reclassification from AOCI, Current Period, Tax	(0.4)	(0.2)	(1.1)	(0.8)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0.6	0.5	1.9	1.4
Removal of obligation relating to Union VEBA
Other Comprehensive Income (Loss), before Tax
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax				106.6
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosures [Abstract]
Reclassification from AOCI, Current Period, Tax				(40.4)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				66.2
Other comprehensive loss relating to available for sale securities
Other Comprehensive Income (Loss), before Tax
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	(0.3)	(0.1)	(0.3)	0.1
Other Comprehensive Income (Loss), before Tax	0.6	(0.5)	1.0	(0.6)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosures [Abstract]
Reclassification from AOCI, Current Period, Tax	0.1	0.1	0.1	0.0
Other Comprehensive Income (Loss), Tax	(0.3)	0.2	(0.4)	0.2
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(0.2)	0.0	(0.2)	0.1
Other Comprehensive Income (Loss), Net of Tax	0.3	(0.3)	0.6	(0.4)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	0.9	(0.4)	1.3	(0.7)
Other Comprehensive Income (Loss) before Reclassifications, Tax	0.4	(0.1)	0.5	(0.2)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0.5	(0.3)	0.8	(0.5)
Foreign currency translation loss
Other Comprehensive Income (Loss), before Tax
Other Comprehensive Income (Loss), before Tax		(0.3)		(0.2)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosures [Abstract]
Other Comprehensive Income (Loss), Tax		0.0		0.0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Other Comprehensive Income (Loss), Net of Tax		$ (0.3)		(0.2)
Foreign currency translation loss | Canadian Pension Plan
Other Comprehensive Income (Loss), before Tax
Canadian Pension foreign currency translation changes (before tax)			0.1
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosures [Abstract]
Canadian Pension foreign currency translation changes (tax)			0.0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Canadian Pension foreign currency translation changes (net of tax)			0.1
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent
Other Comprehensive Income (Loss), before Tax
Other Comprehensive Income (Loss), before Tax	0.1		0.2	(0.2)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosures [Abstract]
Other Comprehensive Income (Loss), Tax	0.0		(0.1)	0.1
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Other Comprehensive Income (Loss), Net of Tax	$ 0.1		$ 0.1	$ (0.1)