Commitments, Guarantees, and Contingencies	12 Months Ended
Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments, Guarantees, and Contingencies	Commitments, Guarantees, and ContingenciesAs of December 31, 2020, we had outstanding letters of credit totaling $0.4 million, which expire by 2022. In addition, as of December 31, 2020, we had two outstanding performance bonds totaling $6.6 million primarily for contracts in our Alternative Fuels Division.

The entire disclosure for commitments and contingencies.

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-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 4
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