INVESTMENT IN UNCONSOLIDATED JOINT VENTURES - Additional Information (Details)	1 Months Ended	3 Months Ended		12 Months Ended
	Apr. 30, 2012	Mar. 31, 2016 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2016 USD ($) Joint_Venture	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Aug. 07, 2015 USD ($)	Mar. 22, 2013	Apr. 15, 2011
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated joint ventures				$ 34,025,000	$ 33,797,000
Number of unconsolidated joint ventures | Joint_Venture				1
Additional return on equity from Company's investments				$ 1,017,000	294,000	$ 1,957,000
Management fees				21,365,000	15,205,000	11,704,000
Expenses from investment				15,861,000	15,849,000	16,864,000
Out-of-Period Adjustment | Noncontrolling Interest in Consolidated Joint Ventures
Schedule of Equity Method Investments [Line Items]
Additional return on equity from Company's investments		$ 900,000
Ladder Capital Realty Income Partnership I LP
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated joint ventures				0	49,000
Minimum average net equity partnership investment as a basis for management fee reduction				100,000,000.0
Management fees			$ 0	6,905	77,447	$ 400,000
Ladder Capital Realty Income Partnership I LP | LP Units
Schedule of Equity Method Investments [Line Items]
Ownership interest (as a percent)									10.00%
Grace Lake JV, LLC
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated joint ventures				$ 3,719,000	2,891,000
Percentage of equity kicker received with right to convert upon capital event	25.00%
Preferred return used to determine distribution of excess cash flow (as a percent)				8.25%
Percentage of distribution of all excess cash flows and all disposition proceeds upon any sale entitled after consideration of preferred return and return of equity remaining in the property to operating partner				25.00%
Percentage of investment of operating partner				75.00%
Grace Lake JV, LLC | LP Units
Schedule of Equity Method Investments [Line Items]
Ownership interest (as a percent)								25.00%
Grace Lake JV, LLC | Limited liability company
Schedule of Equity Method Investments [Line Items]
Ownership interest (as a percent)				25.00%
24 Second Avenue Holdings LLC
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated joint ventures				$ 30,306,000	30,857,000
Ownership interest (as a percent)							73.80%
Amount contributed							$ 31,100,000
Profit multiplier ratio							1.70
Ownership percentage after achievement of profit multiplier ratio							50.00%
Expenses from investment				1,400,000	600,000
Interest costs capitalized				900,000	300,000
24 Second Avenue Holdings LLC | Operating Partner
Schedule of Equity Method Investments [Line Items]
Ownership interest (as a percent)							26.20%
Ownership percentage after achievement of profit multiplier ratio							50.00%
24 Second Avenue Holdings LLC | Co-venturer
Schedule of Equity Method Investments [Line Items]
Loans payable outstanding from unconsolidated joint venture				21,600,000	$ 13,100,000
24 Second Avenue Holdings LLC | Co-venturer | Construction Loan
Schedule of Equity Method Investments [Line Items]
Committed amount on credit agreement				50,500,000
Outstanding amount under credit agreement				21,600,000
Remaining borrowing capacity under credit agreement				$ 0