Notes Payable (Details) - USD ($)		12 Months Ended
	Feb. 02, 2016	Dec. 31, 2016	Jun. 30, 2016	Jan. 12, 2016	Jan. 11, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Notes payable, net		$ 141,882,000				$ 154,460,000
Total debt		142,310,000				155,547,000
Deferred financing fees		(428,000)				(1,087,000)
Notes payable, net of deferred financing fees		141,882,000				154,460,000
Total notes payable obligations		$ 141,882,000				169,291,000
Weighted average interest rate		5.40%
Debt subject to variable interest rate		$ 56,300,000
Real Estate Held For Sale
Debt Instrument [Line Items]
Notes payable, net of deferred financing fees						14,831,000
LIBOR
Debt Instrument [Line Items]
Variable rate basis, term		30 days
Northborough Tower
Debt Instrument [Line Items]
Interest Rate		8.67%
Northborough Tower | Notes Payable
Debt Instrument [Line Items]
Notes payable, net		$ 0				18,516,000
Interest Rate				8.67%	5.67%
Royal Island | Notes Payable
Debt Instrument [Line Items]
Notes payable, net		$ 14,489,000				13,872,000
Interest Rate		15.00%
Amount available to draw on loan			$ 14,500,000
Northpoint Central
Debt Instrument [Line Items]
Notes payable, net		$ 10,602,000				11,720,000
Excess principal balance		$ 3,600,000				3,600,000
Northpoint Central | Notes Payable
Debt Instrument [Line Items]
Interest Rate		5.15%
Chase Park Plaza Hotel and Chase—The Private Residences | Notes Payable
Debt Instrument [Line Items]
Notes payable, net		$ 60,888,000				62,182,000
Interest Rate		4.95%
Interest Rate		4.95%
Variable rate basis		30-day LIBOR
BHFS II, LLC | Notes Payable
Debt Instrument [Line Items]
Notes payable, net		$ 6,733,000				6,856,000
Interest Rate		3.00%
Variable rate basis		30-day LIBOR
BHFS III, LLC | Notes Payable
Debt Instrument [Line Items]
Notes payable, net		$ 6,044,000				6,154,000
Interest Rate		3.00%
Variable rate basis		30-day LIBOR
BHFS IV, LLC | Notes Payable
Debt Instrument [Line Items]
Notes payable, net		$ 12,555,000				12,783,000
Interest Rate		3.00%
Variable rate basis		30-day LIBOR
BHFS Theatre, LLC | Notes Payable
Debt Instrument [Line Items]
Notes payable, net		$ 4,699,000				4,785,000
Interest Rate		3.00%
Variable rate basis		30-day LIBOR
Frisco Square
Debt Instrument [Line Items]
Notes payable, net		$ 30,000,000
Frisco Square | LIBOR
Debt Instrument [Line Items]
Debt instrument, reference rate		0.77167%
The Ablon at Frisco Square
Debt Instrument [Line Items]
Notes payable, net		$ 26,300,000
The Ablon at Frisco Square | Notes Payable
Debt Instrument [Line Items]
Notes payable, net						18,679,000
Interest Rate		2.50%
Variable rate basis		30-day LIBOR
Las Colinas Commons
Debt Instrument [Line Items]
Loan balance		$ 11,300,000				11,300,000
Proceeds from sale of property	$ 14,000,000
Las Colinas Commons | Real Estate Held For Sale
Debt Instrument [Line Items]
Notes payable, net		$ 14,900,000				14,900,000
Las Colinas Commons | Notes Payable
Debt Instrument [Line Items]
Interest Rate		5.15%
Royal Island, Northpoint Central, Chase Park Plaza Hotel, and Ablon at Frisco Square
Debt Instrument [Line Items]
Maturity period		12 months
Minimum
Debt Instrument [Line Items]
Interest rate		3.00%
Maximum
Debt Instrument [Line Items]
Interest rate		15.00%
Frisco Square Investments Debtors | Maximum | Notes Payable
Debt Instrument [Line Items]
Unconditionally guaranteed notes payable		$ 11,200,000
Disposal Group, Held-for-sale, Not Discontinued Operations
Debt Instrument [Line Items]
Notes payable included with obligations related to real estate assets held for sale		0				14,900,000
Deferred financing fees		0				(69,000)
Notes payable, net of deferred financing fees		0				14,831,000
Accounting Standards Update 2015-03
Debt Instrument [Line Items]
Deferred financing fees						0
Notes payable, net of deferred financing fees						154,460
Accounting Standards Update 2015-03 | Actual
Debt Instrument [Line Items]
Deferred financing fees		$ (400,000)				$ (1,200,000)