Fair Value Measurements - Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financial liabilities:
Mortgages payable, net	$ 94,155	$ 205,320
Unsecured notes payable, net	796,247	696,362
Unsecured term loans, net	716,523	447,367
Unsecured revolving line of credit	18,000	273,000
Carrying value
Financial assets:
Derivative asset	0	2,324
Financial liabilities:
Mortgages payable, net	94,155	205,320
Unsecured notes payable, net	796,247	696,362
Unsecured term loans, net	716,523	447,367
Unsecured revolving line of credit	18,000	273,000
Derivative liability	12,288	3,846
Fair value
Financial assets:
Derivative asset	0	2,324
Financial liabilities:
Mortgages payable, net	98,082	208,173
Unsecured notes payable, net	822,883	671,492
Unsecured term loans, net	720,000	449,266
Unsecured revolving line of credit	18,000	272,553
Derivative liability	$ 12,288	$ 3,846