Investments in and Advances to Unconsolidated Affiliates - Unconsolidated Affiliates - Schedule of Condensed Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Combined and Condensed Statements of Income
Revenues	$ 66,075	$ 62,678	$ 192,768	$ 184,181
Operating and other expenses	(59,127)	(56,934)	(172,820)	(161,798)
Depreciation and amortization	(28,676)	(26,652)	(86,755)	(77,245)
(Loss) income from continuing operations before gain on disposition of properties	(7,704)	313	(14,167)	26,392
Company’s equity in earnings of unconsolidated affiliates	376	4,001	7,079	21,044
Unconsolidated Affiliates
Combined and Condensed Statements of Income
Revenues	19,971	20,883	59,730	63,460
Operating and other expenses	(6,028)	(6,847)	(17,479)	(18,985)
Interest expense	(5,240)	(4,788)	(15,365)	(13,967)
Depreciation and amortization	(5,502)	(6,208)	(17,340)	(18,720)
Loss on debt extinguishment	0		0	(154)
(Loss) gain on disposition of properties	(263)		(1,673)	17,778
(Loss) income from continuing operations before gain on disposition of properties	2,938	3,040	7,873	29,412
Operating Partnership, as General Partner or Managing Member
Combined and Condensed Statements of Income
Company’s share of equity in net income of unconsolidated affiliates	1,136	4,544	9,396	23,156
Basis differential amortization	(760)	(543)	(2,317)	(2,112)
Company’s equity in earnings of unconsolidated affiliates	$ 376	$ 4,001	$ 7,079	$ 21,044

Amortization of excess investment.

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The amount of gross profit (loss) reported by an equity method investment of the entity.

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Amount of gain (loss) on sale or disposal of property, plant and equipment assets, excluding oil and gas property and timber property.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

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Amount of the cost of borrowed funds accounted for as interest expense.

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Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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