Fair Value - Summary of Assets Measured at Fair Value on a Nonrecurring Basis (Detail) $ in Millions	Dec. 31, 2018 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	$ 1,039.5
Indefinite-lived intangible assets	3,698.0
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	1,039.5
Indefinite-lived intangible assets	$ 3,698.0