Equity - Accumulated Other Comprehensive Income (Loss) (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income Loss [Line Items]
Gain (loss) on defined benefit plans, income tax expense (benefit)	$ 2.8	$ (0.9)
Unrealized gain (loss) during period on derivatives qualified as cash flow hedges, income tax expense	1.2	0.0
Reclassification to net income of losses (gains) on cash flow hedges, income tax expense (benefit)	(16.6)	1.0
Qualified Pension Plan [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Gain (loss) on defined benefit plans, income tax expense (benefit)	$ 2.8	$ (0.9)