Fair Value Measurements - Financial Assets and Liabilities Not Measured at Fair Value (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Carrying Amount [Member]
Assets:
Cash equivalents	$ 431,280	$ 256,370
Liabilities:
Mortgages payable (excluding deferred debt issuance costs)	1,254,328	1,056,147
Fair Value [Member] | Level 1 [Member]
Assets:
Cash equivalents	431,280	256,370
Fair Value [Member] | Level 2 [Member]
Liabilities:
Mortgages payable (excluding deferred debt issuance costs)	$ 1,245,000	$ 1,045,000