Commitments and Contingencies - Additional Information (Details)	9 Months Ended
	Sep. 30, 2016 ft²
Other Commitments [Line Items]
Prime retail space of building	10,400,000
60 Wall Street [Member]
Other Commitments [Line Items]
Right to acquire period after completion of initial public offering	2 years
718 Fifth Avenue [Member]
Other Commitments [Line Items]
Put right exercise period after sale of interest	4 years
Put right notice period	12 months
Put right actual purchase period	5 years
712 Fifth Avenue [Member]
Other Commitments [Line Items]
Equity method ownership percentage	50.00%
Predecessor [Member] | 718 Fifth Avenue [Member]
Other Commitments [Line Items]
Percentage of tenancy-in-common interest in property	50.00%
Predecessor [Member] | 712 Fifth Avenue [Member]
Other Commitments [Line Items]
Equity method ownership percentage	50.00%
Owned by Affiliate [Member] | Predecessor [Member] | 718 Fifth Avenue [Member] | Third Party Affiliate [Member]
Other Commitments [Line Items]
Equity method ownership percentage	25.00%
Owned by Affiliate [Member] | Parent Company [Member] | Put Right Exercised [Member] | 718 Fifth Avenue [Member]
Other Commitments [Line Items]
Equity method ownership percentage	25.00%
Owned by Affiliate [Member] | Fund II and Fund III [Member] | 60 Wall Street [Member]
Other Commitments [Line Items]
Percentage of ownership in joint venture	62.30%
Owned by Affiliate [Member] | Retail Type Space [Member] | 60 Wall Street [Member]
Other Commitments [Line Items]
Prime retail space of building	1,600,000
Owned by Affiliate [Member] | Retail Type Space [Member] | Predecessor [Member] | 718 Fifth Avenue [Member]
Other Commitments [Line Items]
Prime retail space of building	19,050
Minimum | 60 Wall Street [Member]
Other Commitments [Line Items]
Percentage increase in fair market value of property based on lease amendment	1.00%