Accumulated Other Comprehensive Income (Loss) and Other Comprehensive Income (Loss) - Schedule of Components of Other Comprehensive Income (Loss) that have been Reclassified (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications for the period, before tax	$ (705.5)	$ (745.7)	$ (1,324.5)	$ (1,426.4)
Income tax expense (benefit)	(28.4)	1.9	(51.2)	4.9
Net income (loss) from continuing operations	(27.3)	22.8	(57.6)	20.4
Other Comprehensive Loss Reclassifications [Member] | Change in Derivative Cash Flow Hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications for the period, before tax	0.8	(1.3)	1.2	(8.7)
Income tax expense (benefit)	0.3	(0.5)	0.5	(3.3)
Net income (loss) from continuing operations	0.5	(0.8)	0.7	(5.4)
Other Comprehensive Loss Reclassifications [Member] | Change in Pension and OPEB Liability Adjustments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications for the period, before tax	(2.4)	(1.6)	(4.8)	(3.2)
Income tax expense (benefit)	(0.9)	(0.6)	(1.8)	(1.2)
Net income (loss) from continuing operations	$ (1.5)	$ (1.0)	$ (3.0)	$ (2.0)