Fair Value Measurements (Financial Assets and Liabilities Not Measured at Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Carrying Amount
Assets
Cash equivalents	$ 263,688	$ 173,858
Liabilities [Abstract]
Mortgages payable (excluding deferred debt issuance costs, net)	974,836	974,836
Level 1 | Fair Value
Assets
Cash equivalents	263,688	173,858
Level 2 | Fair Value
Liabilities [Abstract]
Mortgages payable (excluding deferred debt issuance costs, net)	$ 974,000	$ 969,000