Investments in Joint Ventures - EnviroFlight - Additional Information (Details) - USD ($) $ in Thousands	37 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Investment	$ 17,627	$ 18,859
EnviroFlight, LLC
Schedule of Equity Method Investments [Line Items]
Capital contributions	17,000
EnviroFlight, LLC \| Investments In Affiliates
Schedule of Equity Method Investments [Line Items]
Investment	15,829	$ 16,720
Investors \| EnviroFlight, LLC
Schedule of Equity Method Investments [Line Items]
Capital contributions	$ 17,000

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-Section 50
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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