Investments in Other Entities and Noncontrolling Interest in a Subsidiary	3 Months Ended
Mar. 31, 2020
Investments, All Other Investments [Abstract]
Investments in Other Entities and Noncontrolling Interest in a Subsidiary	Note 3— Investments in Other Entities and Noncontrolling Interest in a Subsidiary SAFE&CEC S.r.l. On November 26, 2017, the Company, through its former subsidiary IMW Industries Ltd. (formerly known as Clean Energy Compression Corp.) (“CEC”), entered into an investment agreement with Landi Renzo S.p.A. (“LR”), an alternative fuels company based in Italy. Pursuant to the investment agreement, the Company and LR agreed to combine their respective natural gas fueling compressor manufacturing subsidiaries, CEC and SAFE S.p.A, in a new company, SAFE&CEC S.r.l. (such combination transaction is referred to as the “CEC Combination”). SAFE&CEC S.r.l. is focused on manufacturing, selling and servicing natural gas fueling compressors and related equipment for the global natural gas fueling market. As of the closing of the CEC Combination on December 29, 2017, the Company owns 49% of SAFE&CEC S.r.l. and LR owns 51% of SAFE&CEC S.r.l. The Company accounts for its interest in SAFE&CEC S.r.l. using the equity method of accounting because the Company does not control but has the ability to exercise significant influence over SAFE&CEC S.r.l.’s operations. The Company recorded a loss of $0.4 million and income of $0.0 million from this investment for the three months ended March 31, 2019 and 2020, respectively. The Company has an investment balance in SAFE&CEC S.r.l. of $23.7 million and $22.2 million as of December 31, 2019 and March 31, 2020, respectively. NG Advantage On October 14, 2014, the Company entered into a Common Unit Purchase Agreement (“UPA”) with NG Advantage for a 53.3% controlling interest in NG Advantage. NG Advantage is engaged in the business of transporting CNG in high-capacity trailers to industrial and institutional energy users, such as hospitals, food processors, manufacturers and paper mills that do not have direct access to natural gas pipelines. NG Advantage has entered into an arrangement with BP Products North America (“BP”) for the supply, sale and reservation of a specified volume of CNG transportation capacity until March 2022. On February 28, 2018, the Company entered into a guaranty agreement with NG Advantage and BP pursuant to which the Company guarantees NG Advantage’s payment obligations to BP in the event of default by NG Advantage under the supply arrangement, in an amount up to an aggregate of $30.0 million plus related fees. This guaranty is in effect until thirty days following the Company’s notice to BP of its termination. As initial consideration for the guaranty agreement, NG Advantage issued to the Company 19,660 common units, which increased the Company’s controlling interest in NG Advantage from 53.3% to 53.5%. On October 1, 2018, the Company purchased 1,000,001 common units from NG Advantage for an aggregate cash purchase price of $5.0 million. This purchase increased Clean Energy’s controlling interest in NG Advantage from 53.5% to 61.7%. In each month from November 2018 through February 2019, the Company was issued 100,000 additional common units of NG Advantage, for a total of 400,000 common units, pursuant to the guaranty agreement entered in February 2018. The issuance of 400,000 additional common units increased the Company’s controlling interest in NG Advantage to 64.6% as of March 31, 2019. On February 15, 2019, NG Advantage and the Company entered into a transaction pursuant to which the Company agreed to lend to NG Advantage up to $5.0 million in accordance with the terms of a delayed draw convertible promissory note (the “2019 Note”). NG Advantage simultaneously drew $2.5 million under the 2019 Note, and on April 15, 2019, NG Advantage drew the remaining $2.5 million under the 2019 Note. As discussed below, on June 28, 2019, all unpaid principal and accrued interest under the 2019 Note was subsumed within the June 2019 Convertible Note (as defined below). On May 17, 2019, the Company agreed to lend to NG Advantage up to $0.5 million in accordance with the terms of a promissory note (the “2019 Bridge Loan”). On June 11, 2019, NG Advantage drew $0.1 million under the 2019 Bridge Loan. As discussed below, on June 28, 2019, all unpaid principal and accrued interest under the 2019 Bridge Loan was subsumed within the June 2019 Convertible Note. On June 28, 2019, the Company agreed to lend to NG Advantage up to $15.2 million in accordance with the terms of a delayed draw convertible promissory note (the “June 2019 Convertible Note”). NG Advantage simultaneously drew $3.5 million under the June 2019 Convertible Note. The outstanding principal and accrued interest under the 2019 Note and 2019 Bridge Loan were incorporated into the June 2019 Convertible Note, which resulted in the cancellation of the 2019 Note and 2019 Bridge Loan. In connection with the June 2019 Convertible Note, NG Advantage issued to the Company a warrant to purchase 86,879 common units. During the period of July 1, 2019 through November 26, 2019, NG Advantage drew an additional $7.4 million under the June 2019 Convertible Note. As discussed below, on November 27, 2019, all unpaid principal and accrued interest under the June 2019 Convertible Note was subsumed within the November 2019 Convertible Note (as defined below). On November 27, 2019, the Company agreed to lend to NG Advantage up to $26.7 million in accordance with the terms of a delayed draw convertible promissory note (the “November 2019 Convertible Note”). NG Advantage simultaneously drew $3.4 million under the November 2019 Convertible Note. The outstanding principal and accrued interest under the June 2019 Convertible Note were incorporated into the November 2019 Convertible Note, which resulted in the cancellation of the June 2019 Convertible Note. All outstanding principal under the November 2019 Convertible Note bore interest at a rate of 12.0% per annum, and all unpaid principal and accrued interest under the November 2019 Convertible Note was due on the earlier of December 31, 2019, subject to extension at the Company's discretion, or the occurrence of an event of default (subject to notice requirements and cure periods in certain circumstances). In connection with the November 2019 Convertible Note, NG Advantage issued to the Company a warrant to purchase 2,000,000 common units. In December 2019, the maturity date of the November 2019 Convertible Note was extended at the Company’s discretion and NG Advantage drew an additional $6.6 million under the November 2019 Convertible Note. As of December 31, 2019, NG Advantage had an outstanding balance of $26.7 million, plus accrued and unpaid interest, under the November 2019 Convertible Note. On February 6, 2020, the Company converted the outstanding principal and accrued interest under the November 2019 Convertible Note into common units of NG Advantage resulting in an increase in the Company’s controlling interest in NG Advantage to 93.2%. On February 29, 2020, NG Advantage issued to the Company 283,019 common units pursuant to the guaranty agreement entered in February 2018, which increased the Company’s controlling interest in NG Advantage to 93.3% as of March 31, 2020. The Company recorded a loss attributable to the noncontrolling interest in NG Advantage of $1.9 million and $0.8 million for the three months ended March 31, 2019 and 2020, respectively. The value of the noncontrolling interest was $9.6 million and $10.2 million as of December 31, 2019 and March 31, 2020, respectively.

Note 3— Investments in Other Entities and Noncontrolling Interest in a Subsidiary

SAFE&CEC S.r.l.

On November 26, 2017, the Company, through its former subsidiary IMW Industries Ltd. (formerly known as Clean Energy Compression Corp.) (“CEC”), entered into an investment agreement with Landi Renzo S.p.A. (“LR”), an alternative fuels company based in Italy. Pursuant to the investment agreement, the Company and LR agreed to combine their respective natural gas fueling compressor manufacturing subsidiaries, CEC and SAFE S.p.A, in a new company, SAFE&CEC S.r.l. (such combination transaction is referred to as the “CEC Combination”). SAFE&CEC S.r.l. is focused on manufacturing, selling and servicing natural gas fueling compressors and related equipment for the global natural gas fueling market. As of the closing of the CEC Combination on December 29, 2017, the Company owns 49% of SAFE&CEC S.r.l. and LR owns 51% of SAFE&CEC S.r.l.

The Company accounts for its interest in SAFE&CEC S.r.l. using the equity method of accounting because the Company does not control but has the ability to exercise significant influence over SAFE&CEC S.r.l.’s operations. The Company recorded a loss of $0.4 million and income of $0.0 million from this investment for the three months ended March 31, 2019 and 2020, respectively. The Company has an investment balance in SAFE&CEC S.r.l. of $23.7 million and $22.2 million as of December 31, 2019 and March 31, 2020, respectively.

NG Advantage

On October 14, 2014, the Company entered into a Common Unit Purchase Agreement (“UPA”) with NG Advantage for a 53.3% controlling interest in NG Advantage. NG Advantage is engaged in the business of transporting CNG in high-capacity trailers to industrial and institutional energy users, such as hospitals, food processors, manufacturers and paper mills that do not have direct access to natural gas pipelines.

NG Advantage has entered into an arrangement with BP Products North America (“BP”) for the supply, sale and reservation of a specified volume of CNG transportation capacity until March 2022. On February 28, 2018, the Company entered into a guaranty agreement with NG Advantage and BP pursuant to which the Company guarantees NG Advantage’s payment obligations to BP in the event of default by NG Advantage under the supply arrangement, in an amount up to an aggregate of $30.0 million plus related fees. This guaranty is in effect until thirty days following the Company’s notice to BP of its termination. As initial consideration for the guaranty agreement, NG Advantage issued to the Company 19,660 common units, which increased the Company’s controlling interest in NG Advantage from 53.3% to 53.5%.

On October 1, 2018, the Company purchased 1,000,001 common units from NG Advantage for an aggregate cash purchase price of $5.0 million. This purchase increased Clean Energy’s controlling interest in NG Advantage from 53.5% to 61.7%.

In each month from November 2018 through February 2019, the Company was issued 100,000 additional common units of NG Advantage, for a total of 400,000 common units, pursuant to the guaranty agreement entered in February 2018. The issuance of 400,000 additional common units increased the Company’s controlling interest in NG Advantage to 64.6% as of March 31, 2019.

On February 15, 2019, NG Advantage and the Company entered into a transaction pursuant to which the Company agreed to lend to NG Advantage up to $5.0 million in accordance with the terms of a delayed draw convertible promissory note (the “2019 Note”). NG Advantage simultaneously drew $2.5 million under the 2019 Note, and on April 15, 2019, NG Advantage drew the remaining $2.5 million under the 2019 Note. As discussed below, on June 28, 2019, all unpaid principal and accrued interest under the 2019 Note was subsumed within the June 2019 Convertible Note (as defined below).

On May 17, 2019, the Company agreed to lend to NG Advantage up to $0.5 million in accordance with the terms of a promissory note (the “2019 Bridge Loan”). On June 11, 2019, NG Advantage drew $0.1 million under the 2019 Bridge Loan. As discussed below, on June 28, 2019, all unpaid principal and accrued interest under the 2019 Bridge Loan was subsumed within the June 2019 Convertible Note.

On June 28, 2019, the Company agreed to lend to NG Advantage up to $15.2 million in accordance with the terms of a delayed draw convertible promissory note (the “June 2019 Convertible Note”). NG Advantage simultaneously drew $3.5 million under the June 2019 Convertible Note. The outstanding principal and accrued interest under the 2019 Note and 2019 Bridge Loan were incorporated into the June 2019 Convertible Note, which resulted in the cancellation of the 2019 Note and 2019 Bridge Loan. In connection with the June 2019 Convertible Note, NG Advantage issued to the Company a warrant to purchase 86,879 common units. During the period of July 1, 2019 through November 26, 2019, NG Advantage drew an additional $7.4 million under the June 2019 Convertible Note. As discussed below, on November 27, 2019, all unpaid principal and accrued interest under the June 2019 Convertible Note was subsumed within the November 2019 Convertible Note (as defined below).

On November 27, 2019, the Company agreed to lend to NG Advantage up to $26.7 million in accordance with the terms of a delayed draw convertible promissory note (the “November 2019 Convertible Note”). NG Advantage simultaneously drew $3.4 million under the November 2019 Convertible Note. The outstanding principal and accrued interest under the June 2019 Convertible Note were incorporated into the November 2019 Convertible Note, which resulted in the cancellation of the June 2019 Convertible Note. All outstanding principal under the November 2019 Convertible Note bore interest at a rate of 12.0% per annum, and all unpaid principal and accrued interest under the November 2019 Convertible Note was due on the earlier of December 31, 2019, subject to extension at the Company's discretion, or the occurrence of an event of default (subject to notice requirements and cure periods in certain circumstances). In connection with the November 2019 Convertible Note, NG Advantage issued to the Company a warrant to purchase 2,000,000 common units. In December 2019, the maturity date of the November 2019 Convertible Note was extended at the Company’s discretion and NG Advantage drew an additional $6.6 million under the November 2019 Convertible Note. As of December 31, 2019, NG Advantage had an outstanding balance of $26.7 million, plus accrued and unpaid interest, under the November 2019 Convertible Note. On February 6, 2020, the Company converted the outstanding principal and accrued interest under the November 2019 Convertible Note into common units of NG Advantage resulting in an increase in the Company’s controlling interest in NG Advantage to 93.2%.

On February 29, 2020, NG Advantage issued to the Company 283,019 common units pursuant to the guaranty agreement entered in February 2018, which increased the Company’s controlling interest in NG Advantage to 93.3% as of March 31, 2020.

The Company recorded a loss attributable to the noncontrolling interest in NG Advantage of $1.9 million and $0.8 million for the three months ended March 31, 2019 and 2020, respectively. The value of the noncontrolling interest was $9.6 million and $10.2 million as of December 31, 2019 and March 31, 2020, respectively.