Other Assets and Intangibles - Summary of Amortization Expense Related to the Intangibles, Excluding Above and Below-Market Leases (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Intangible Assets Net Excluding Goodwill [Abstract]
Amortization expense	$ 60.7	$ 72.1	$ 92.6