Fair Value - Summary of Assets Measured at Fair Value on a Nonrecurring Basis (Detail) - Fair Value, Measurements, Nonrecurring - Level 3 - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	$ 0.0	$ 1,039.5
Indefinite-lived assets	$ 1,365.2	$ 3,698.0