Common Equity - Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Derivative contracts, Income tax (expense) benefit	$ 6.7	$ 0.8	$ 7.3	$ 1.6
Total reclassifications, Net of tax	(17.5)	(1.4)	(19.0)	(2.6)
Total reclassifications, Net of tax	(17.5)	(0.9)	(19.0)	(1.6)
Gains (Losses) on Cash Flow Hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Derivative contracts, Total before tax	(24.2)	(2.2)	(26.3)	(4.2)
Derivative contracts, Income tax (expense) benefit	6.7	0.8	7.3	1.6
Total reclassifications, Net of tax	(17.5)	(1.4)	(19.0)	(2.6)
Gains (Losses) on Cash Flow Hedges [Member] | Interest Expense, Net [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Derivative contracts, Total before tax	(5.0)	(2.2)	(5.0)	(4.2)
Gains (Losses) on Cash Flow Hedges [Member] | Other Operating Expenses (Income) , Net [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Derivative contracts, Total before tax	(22.7)		(27.6)
Gains (Losses) on Cash Flow Hedges [Member] | Cost of Sales [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Derivative contracts, Total before tax	3.5		6.3
Defined Benefit Pension [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior service credits (costs), SG&A	0.7	0.8	1.4	1.5
Amortization of actuarial gains (losses), SG&A	$ (0.7)	0.1	$ (1.4)	0.1
Defined benefit pension plan expense before tax		0.9		1.6
Defined benefit, Income tax (expense) benefit		(0.4)		(0.6)
Total reclassifications, Net of tax		$ 0.5		$ 1.0