Other Comprehensive Income - Accumulated Other Comprehensive Loss (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income Loss [Line Items]
Net income discontinued operations settlement	$ 7.8
Net unrealized losses from cash flow hedges, tax benefit	4.7	4.9
Pension Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Unrecognized pension and other benefit loss, prior service cost (credit) and transition obligation, tax expense (benefit)	12.3	12.6
Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Unrecognized pension and other benefit loss, prior service cost (credit) and transition obligation, tax expense (benefit)	$ 4.4	$ 9.1