Fair Value Measurements of Assets and Liabilities - Schedule of Nonfinancial Assets Measured at Fair Value on Nonrecurring Basis (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Goodwill			$ 41.0
Indefinite-lived intangible assets	34.2	21.0	24.2
Goodwill	0	0	96.0
Indefinite-lived intangible assets	14.2	2.8	11.6
Fair Value Measurements at Reporting Date Using: Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Goodwill			41.0
Indefinite-lived intangible assets	$ 34.2	$ 21.0	$ 24.2