Investments in and Advances to Unconsolidated Ventures (Details) (USD $)	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended		1 Months Ended	3 Months Ended	6 Months Ended						1 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2013 Milford Plaza hotel	Jun. 30, 2013 Milford Plaza hotel	Apr. 30, 2013 Milford Plaza hotel	Feb. 28, 2013 PE Investment I item	Jun. 30, 2013 PE Investment I	Jun. 30, 2013 PE Investment I	Jun. 30, 2013 PE Investment I Cash distribution until NorthStar Entities receive a 1.5x multiple on all of their invested capital	Jun. 30, 2013 PE Investment I Cash distribution until NorthStar Entities receive a 1.5x multiple on all of their invested capital Class B Partner	Jun. 30, 2013 PE Investment I Cash distribution until return of then remaining June 30, 2012 capital of Class B Partner	Jun. 30, 2013 PE Investment I Remaining cash distribution	Jun. 30, 2013 PE Investment I Remaining cash distribution Class B Partner	Feb. 28, 2013 PE Investment I Sponsor	Jun. 30, 2013 PE Investment II item	Jun. 30, 2013 PE Investment II	Sep. 30, 2012 PE Investment II	Jun. 30, 2013 PE Investment II Sponsor	Jun. 30, 2013 PE Investment II Vintage Funds
Investments in and advances to unconsolidated ventures
Amount funded at initial closing of real estate private equity						$ 118,000,000
Amount contributed in the joint venture														282,100,000
Ownership interest held by the entity together with sponsor (as a percent)						51.00%
Cash distribution to the NorthStar Entities (as a percent)									85.00%		15.00%	51.00%
Cash distribution to the Class B Partner (as a percent)									85.00%	15.00%			49.00%
Multiplier factor for cash distribution to the NorthStar Entities									1.5
Equity recognized in earnings (losses)	5,827,000	9,042,000	(200,000)	(200,000)			6,000,000	9,200,000
Net distribution received								23,700,000
Contribution made								7,500,000
Number of real estate private equity funds contributed						47									25
Aggregate reported net asset value																	925,400,000
Ownership interest in amount funded (as a percent)						29.50%	29.50%	29.50%						70.50%	15.00%	15.00%		70.00%	15.00%
Amount to be paid to the Seller for all of the fund interests																509,900,000
Percentage of September 30, 2012 NAV paid as Initial Amount to Seller for all of the fund interests																55.00%
Deferred Amount paid to Seller for remaining of the fund interests																415,500,000
Percentage of September 30, 2012 NAV paid as Deferred Amount to Seller for all of the fund interests																45.00%
Entity's share in Initial Amount																76,500,000
Entity's share in Deferred Amount																62,300,000
Estimated future capital commitments							11,100,000									8,800,000
Period in which distribution will be made on priority basis since beginning, on the first day of the fiscal quarter following the closing date of each fund interest																3 years
Percentage of distribution to PE Investment II																85.00%
Percentage of distribution to Seller																15.00%
Reduction in deferred amount as a percentage of amortization amount																15.00%
Percentage of distributions receivable by funds following the payment of the Deferred Amount (as a percent)																100.00%
Distribution period																4 years
Amount deposited in connection with subscription agreement															50,000,000	50,000,000
Ownership percentage			35.00%	35.00%	35.00%
Carrying value of investments			$ 500,000	$ 500,000			$ 111,100,000	$ 111,100,000							$ 7,500,000	$ 7,500,000