Debt - Summary of Financial Covenants (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Debt Disclosure [Abstract]
Minimum fixed charge coverage ratio, actual	2.29%
Maximum total leverage ratio, actual	2.61%
Minimum liquidity, actual	$ 1,400
Minimum fixed charge coverage ratio, requirement	1.50%
Maximum total leverage ratio, requirement	4.25%
Minimum liquidity, requirement	$ 200