Debt - Schedule of Carrying Amounts and Fair Values of Financial Instruments (Detail) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Carrying Amount [Member] | Senior Secured Credit Facilities [Member]
Financial liabilities:
Credit facility	$ 5,906.0	$ 8,319.1
Carrying Amount [Member] | 5.5% Senior Notes due 2027 [Member]
Financial liabilities:
Senior notes	2,000.0
Carrying Amount [Member] | Other Indebtedness [Member]
Financial liabilities:
Credit facility	26.3	28.2
Fair Value [Member] | Senior Secured Credit Facilities [Member]
Financial liabilities:
Credit facility	5,881.3	7,847.4
Fair Value [Member] | 5.5% Senior Notes due 2027 [Member]
Financial liabilities:
Credit facility	2,075.0
Fair Value [Member] | Other Indebtedness [Member]
Financial liabilities:
Credit facility	$ 26.5	$ 28.3