Fair Value (Details) - USD ($)	Dec. 31, 2017	Aug. 31, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair value of investment in unconsolidated venture	$ 5,400,000
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate debt investments, net	34,827,778		$ 0
Mezzanine Loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate debt investments, net	34,827,778
Times Square, New York \| Corporate Joint Venture \| Mezzanine Loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Face amount of mortgages	$ 15,000,000.0
Ownership percentage	63.30%
Proportionate interest in debt instrument	$ 9,500,000
West Village, New York
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Proportionate interest in debt instrument		$ 12,000,000
West Village, New York \| Corporate Joint Venture \| Mezzanine Loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Face amount of mortgages	$ 20,000,000.0
Ownership percentage	60.00%
Proportionate interest in debt instrument	$ 12,000,000
Principal Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate debt investments, net	35,000,000		0
Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate debt investments, net	34,827,778		0
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate debt investments, net	$ 35,000,000		$ 0

NorthStar/RXR New York Metro Real Estate, Inc. 10-K