Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Foreign Currency Translation [Abstract]
Balance at beginning of period		$ (0.6)	$ (2.2)	$ (2.1)	$ 1.0
Foreign currency translation gain (loss)		(1.1)	1.2	0.4	(2.0)
Balance at end of period		(1.7)	(1.0)	(1.7)	(1.0)
Cash flow hedges
Balance at beginning of period		(28.6)	(32.3)	(34.0)	(32.2)
Other comprehensive income (loss):
Gains (losses) arising in period		40.7	(1.5)	32.9	(19.5)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax		2.9	0.0	2.9	0.0
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax		37.8	(1.5)	30.0	(19.5)
Reclassification of losses (gains) to net income (loss)		14.5	9.3	27.7	27.2
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax		2.3	0.0	2.3	0.0
Net amount of reclassification of losses (gains) to net income (loss)		12.2	9.3	25.4	27.2
Total other comprehensive income (loss), net of tax		50.0	7.8	55.4	7.7
Balance at end of period		21.4	(24.5)	21.4	(24.5)
Unrealized holding gains on securities
Balance at beginning of period		0.0	0.4	0.0	0.4
Balance at end of period		0.0	0.4	0.0	0.4
Pension and OPEB plans
Balance at beginning of period		(159.0)	(180.5)	(151.1)	(173.6)
Reclassification to net income (loss):
Reclassification of prior service cost (credits) included in net income (loss)		(13.8)	(15.0)	(27.6)	(30.1)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax		6.0	8.2	11.9	16.4
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax		(7.8)	(6.8)	(15.7)	(13.7)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Tax		(1.3)	0.0	(1.3)	0.0
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Net of Tax		(6.5)	(6.8)	(14.4)	(13.7)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax		(6.5)	(6.8)	(14.4)	(13.7)
Balance at end of period		(165.5)	(187.3)	(165.5)	(187.3)
Cost of Sales [Member]
Other comprehensive income (loss):
Reclassification of losses (gains) to net income (loss)	[1]	14.5	9.3	27.7	27.2
Pension and OPEB Expense (Income) [Member]
Reclassification to net income (loss):
Reclassification of prior service cost (credits) included in net income (loss)	[2]	(13.8)	(15.0)	(27.6)	(30.1)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax	[2]	$ 6.0	$ 8.2	$ 11.9	$ 16.4

[1] Included in cost of products sold.

[2] Included in pension and OPEB expense (income).