Investment in Unconsolidated and Consolidated Joint Ventures - Investment Information (Details)	1 Months Ended		3 Months Ended			9 Months Ended
	Sep. 30, 2016 ft²	Aug. 31, 2016 USD ($) ft²	Sep. 30, 2017 USD ($) a	Sep. 30, 2016 USD ($)	Jun. 30, 2013 USD ($) ft² member	Sep. 30, 2017 USD ($) a ft² joint_venture	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2013 USD ($)
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated joint ventures			$ 28,911,000			$ 28,911,000		$ 33,803,000
Equity in earnings (loss)			1,724,000	$ 2,353,000		3,512,000	$ 5,650,000
Equity			28,911,000			28,911,000		33,803,000
Debt			111,590,000			111,590,000		97,318,000
Distribution of earnings from unconsolidated joint ventures						7,200,000	$ 4,500,000
Promissory note agreement
Schedule of Equity Method Investments [Line Items]
Debt instrument face amount									$ 4,750,000
Line of Credit
Schedule of Equity Method Investments [Line Items]
Summarized financial information, maximum borrowing capacity			$ 52,000,000			$ 52,000,000
Petro Travel Plaza Holdings LLC
Schedule of Equity Method Investments [Line Items]
Unconsolidated joint ventures, voting rights						50.00%
Unconsolidated joint ventures, ownership interest			60.00%			60.00%
Equity			$ 15,846,000			$ 15,846,000		18,372,000
Debt			15,278,000			$ 15,278,000		15,275,000
Majestic Realty Co.
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated joint ventures		$ 24,773,000
Number of joint venture contracts | joint_venture						2
Area of building owned and leased | ft²		651,909
Majestic Realty Co. | Promissory note agreement
Schedule of Equity Method Investments [Line Items]
Debt instrument face amount		$ 21,080,000
TRC-MRC 2 LLC
Schedule of Equity Method Investments [Line Items]
Equity			0			$ 0		1,431,000
Debt			21,080,000			21,080,000		21,080,000
Deficit balance			54,000			54,000
TRCC-East
Schedule of Equity Method Investments [Line Items]
Area of building owned and leased | ft²	480,480
Distribution of earnings from unconsolidated joint ventures						1,952,000
Deficit balance			4,000			4,000
Number of acres for development | ft²					326,000
TRC-MRC 1 LLC
Schedule of Equity Method Investments [Line Items]
Equity			0			0		224,000
Debt			16,150,000			16,150,000		0
Construction Loan			25,000,000			$ 25,000,000
Rockefeller Joint Ventures
Schedule of Equity Method Investments [Line Items]
Number of joint venture contracts | joint_venture						3
Investment in unconsolidated joint ventures			$ 13,065,000			$ 13,065,000
Number of acres for development | a						91
Development of land in TRCC including pursuing foreign trade zone (up to) | a			500			500
Rockefeller Joint Ventures | Building Development
Schedule of Equity Method Investments [Line Items]
Number of joint venture contracts | joint_venture						2
Five West Parcel
Schedule of Equity Method Investments [Line Items]
Unconsolidated joint ventures, ownership interest			50.00%			50.00%
Equity			$ 2,710,000			$ 2,710,000		2,837,000
Area of building owned and leased | ft²						606,000
Debt			$ 9,847,000			$ 9,847,000		10,251,000
18-19 West LLC
Schedule of Equity Method Investments [Line Items]
Unconsolidated joint ventures, ownership interest			50.00%			50.00%
Equity			$ 1,733,000			$ 1,733,000		1,741,000
Debt			0			$ 0		0
Number of acres for development | a						61.5
TRCC/Rock Outlet Center
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated joint ventures					$ 87,000,000
Equity			8,622,000			$ 8,622,000		9,198,000
Debt			49,235,000			49,235,000		50,712,000
Construction loan percent of costs					60.00%
Equity contributions, percent					40.00%
Number of members | member					2
Centennial
Schedule of Equity Method Investments [Line Items]
Debt			$ 0			$ 0		$ 0
Consolidated joint venture, ownership interest			87.71%			87.71%