Mortgage Notes, Term Loan, and Revolving Credit Facility - Summary of Mortgage Notes, Term Loan, and Revolving Credit Facility Secured by Company's Properties (Parenthetical) (Details)	6 Months Ended
	Jun. 30, 2017
Debt Instrument [Line Items]
Debt instrument, Interest only payments term	first 60 months
Debt instrument, Principal and interest payments term	final 24 months
One-Month U.S. Dollar-Denominated London Interbank Offer Rate [Member]
Debt Instrument [Line Items]
Debt instrument, Interest rate	1.20%
55 West [Member] | Mortgage Notes [Member]
Debt Instrument [Line Items]
Debt instrument, Initial maturity date	May 09, 2019
Debt instrument, Extension term	three one-year