Investment in Unconsolidated and Consolidated Joint Ventures - Investment Information (Details)			1 Months Ended		3 Months Ended			9 Months Ended		12 Months Ended
		Apr. 01, 2019 USD ($)	Apr. 30, 2019 USD ($) ft²	Nov. 30, 2018 ft²	Dec. 31, 2019	Sep. 30, 2019 USD ($) a	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) a ft² joint_venture	Sep. 30, 2018 USD ($)	Dec. 31, 2013 ft²	Dec. 31, 2018 USD ($)	Jun. 01, 2018 USD ($)
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated joint ventures						$ 42,177,000		$ 42,177,000			$ 28,602,000
Equity in earnings (loss)						2,199,000	$ 1,592,000	5,046,000	$ 2,411,000
Equity						42,177,000		42,177,000			28,602,000
Debt						86,845,000		86,845,000			121,326,000
Value of land contributed	[1]							5,854,000	$ 0
Centennial
Schedule of Equity Method Investments [Line Items]
Noncontrolling interest balance						$ 11,039,000		$ 11,039,000			13,172,000
Consolidated joint venture, ownership interest						92.50%		92.50%
Petro Travel Plaza Holdings, LLC
Schedule of Equity Method Investments [Line Items]
Unconsolidated joint ventures, ownership interest						50.00%		50.00%
Right and share of profit and loss						60.00%		60.00%
Equity						$ 24,145,000		$ 24,145,000			18,426,000
Debt						15,286,000		15,286,000			15,283,000
Majestic Realty Co.
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated joint ventures						24,773,000		$ 24,773,000
Number of joint venture contracts | joint_venture								3
Area of building owned and leased | ft²								651,909
TRC-MRC 3, LLC
Schedule of Equity Method Investments [Line Items]
Equity						5,954,000		$ 5,954,000			0
Number of acres for development | ft²			579,040	579,040
Debt						23,327,000		23,327,000			0
Profit margin		$ 1,533,000	$ 1,500,000
Deferred profit margin		1,532,000	1,500,000
TRC-MRC 3, LLC | Land
Schedule of Equity Method Investments [Line Items]
Value of land contributed		$ 5,854,000	$ 5,900,000
TRC-MRC 3, LLC | Scenario, Forecast
Schedule of Equity Method Investments [Line Items]
Lease agreement, rentable space					67.00%
TRC-MRC 2, LLC
Schedule of Equity Method Investments [Line Items]
Equity						0		0			0
Debt						(24,597,000)		(24,597,000)			25,014,000
Debt instrument face amount												$ 25,240,000
Deficit balance						2,499,000		$ 2,499,000
TRCC-East
Schedule of Equity Method Investments [Line Items]
Number of acres for development | ft²										326,000
Area of building owned and leased | ft²								480,480
Deficit balance						354,000		$ 354,000
TRC-MRC 1, LLC
Schedule of Equity Method Investments [Line Items]
Equity						0		0			0
Debt						24,667,000		24,667,000			25,030,000
Construction Loan						25,030,000		$ 25,030,000
Rockefeller Joint Ventures
Schedule of Equity Method Investments [Line Items]
Number of joint venture contracts | joint_venture								3
Number of acres for development | a								91
Investment in unconsolidated joint ventures						$ 12,078,000		$ 12,078,000
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, LLC
Schedule of Equity Method Investments [Line Items]
Unconsolidated joint ventures, ownership interest						50.00%		50.00%		50.00%
Equity						$ 3,057,000		$ 3,057,000			2,691,000
Debt						8,769,000		$ 8,769,000			9,173,000
Area of building owned and leased | ft²								606,000
Option to extend, joint venture								3 years
18-19 West, LLC
Schedule of Equity Method Investments [Line Items]
Equity						1,743,000		$ 1,743,000			1,783,000
Debt						0		$ 0			0
Number of acres for development | a								63.5
TRCC/Rock Outlet Center, LLC
Schedule of Equity Method Investments [Line Items]
Equity						7,278,000		$ 7,278,000			5,702,000
Debt						$ 39,393,000		$ 39,393,000			$ 46,826,000

[1] In April 2019, the Company contributed land with a fair value of $5.9 million to TRC-MRC 3, LLC an unconsolidated joint venture formed to pursue the development, construction, leasing, and management of a 579,040 square foot industrial building on the Company's property at TRCC-East. The total cost of the land, inclusive of transaction costs was $2.9 million. The Company recognized $1.5 million in profit and deferred $1.5 million after applying the five-step revenue recognition model in accordance with Accounting Standards Codification (ASC) Topic 606 — Revenue From Contracts With Customers and ASC Topic 323, Investments — Equity Method and Joint Ventures. Historically, cash outflows related to land development expenditures were accounted for within investing activities. For consistency, the Company will continue to classify cash outflows and cash inflows related to land development as investing activities.