Fair Value Measurements - Financial Assets and Liabilities Not Measured at Fair Value (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Carrying Amount
Assets:
Cash equivalents	$ 248,850	$ 173,858
Liabilities:
Mortgages payable (excluding deferred debt issuance costs, net)	974,836	974,836
Fair Value | Level 1
Assets:
Cash equivalents	248,850	173,858
Fair Value | Level 2
Liabilities:
Mortgages payable (excluding deferred debt issuance costs, net)	$ 972,000	$ 969,000