Other Assets and Intangibles - Summary of Estimated Net Future Amortization Associated with Above and Below-Market Leases (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Intangible Assets Net Excluding Goodwill [Abstract]
Future amortization income, 2018	$ 7.1
Future amortization income, 2019	7.8
Future amortization income, 2020	7.9
Future amortization income, 2021	8.1
Future amortization income, 2022	$ 8.4