Fair Value Measurements - Summary of the Face Values, Carrying Amounts and Fair Values of Company's Financial Instruments Using Level 2 Inputs, for Senior Unsecured Notes Payable, and Level 3 Inputs, for all Other Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Financial assets:
Preferred equity investment - face value	$ 7,500	$ 7,500
Preferred equity investment	8,200
Financial liabilities:
Senior unsecured notes payable	260,000	260,000
Mortgage notes payable	95,696	98,205
Level 2 | Senior unsecured notes payable
Financial liabilities:
Financial liabilities - face value	260,000	260,000
Level 3 | Mortgage notes payable
Financial liabilities:
Financial liabilities - face value	95,696	98,205
Fair Value
Financial assets:
Preferred equity investment	8,229	7,532
Fair Value | Level 2
Financial liabilities:
Senior unsecured notes payable	266,500	265,200
Fair Value | Level 3
Financial liabilities:
Mortgage notes payable	98,128	101,822
Carrying Amount
Financial assets:
Preferred equity investment	8,229	7,532
Carrying Amount | Level 2
Financial liabilities:
Senior unsecured notes payable	260,000	260,000
Carrying Amount | Level 3
Financial liabilities:
Mortgage notes payable	$ 95,696	$ 98,205