Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) Derivative	Dec. 31, 2016	Dec. 31, 2015
Summary Of Significant Accounting Policies [Line Items]
Expected lease-up periods for estimating lost rentals, in months	6 months
Percentage of ordinary taxable income to be distributed for real estate investment trust qualification	90.00%	90.00%	90.00%
Number of years of federal income tax at corporate rates on failure to qualify as REIT	4 years
Number of derivative or hedging activity | Derivative	0
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Stock award vesting period in years	10 years
Accounting Standards Update No. 2017-01 [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Decrease normalized funds from operations	$ (1)
Accounting Standards Update No. 2017-01 [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Decrease normalized funds from operations	(2)
Accounting Standards Update 2014-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Adjustment to retained earnings	$ 2
Consolidated Entities [Member]
Summary Of Significant Accounting Policies [Line Items]
Equity method investment, ownership percentage	100.00%
Time-Based Awards [Member]
Summary Of Significant Accounting Policies [Line Items]
Stock award vesting period in years	3 years
Market Conditions Based Awards [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Stock award vesting period in years	3 years
Market Conditions Based Awards [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Stock award vesting period in years	5 years