Description of Organization and Business Operations	12 Months Ended
Dec. 31, 2019
Description of Organization and Business Operations [Abstract]
DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS	NOTE 1. DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS *Organization and General* Tortoise Acquisition Corp. (the "Company") was incorporated in Delaware on November 7, 2018. The Company was formed for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses (the "Initial Business Combination"). The Company is an "emerging growth company," as defined in Section 2(a) of the Securities Act of 1933, as amended (the "Securities Act"), as modified by the Jumpstart Our Business Startups Act of 2012 (the "JOBS Act"). As of December 31, 2019, the Company had not commenced any operations. All activity for the period from November 7, 2018 (date of inception) to December 31, 2019 relates to the Company's formation and the initial public offering (the "Initial Public Offering") described below, and since the closing of the Initial Public Offering, the identification and evaluation of prospective acquisition targets for an Initial Business Combination and ongoing administrative and compliance matters. The Company will not generate any operating revenues until after completion of its Initial Business Combination, at the earliest. The Company generates non-operating income in the form of interest income earned on investments from the net proceeds derived from the Initial Public Offering. *Sponsor and Initial Public Offering* The Company's sponsor is Tortoise Sponsor LLC, a Delaware limited liability company (the "Sponsor"). As described in Note 3, on March 4, 2019, the Company consummated the Initial Public Offering of 23,300,917 of its units (the "Units"), including 800,917 Units that were issued pursuant to the underwriters' partial exercise of their over-allotment option, generating gross proceeds of approximately $233.0 million. As described in Note 4, on March 4, 2019, simultaneously with the closing of the Initial Public Offering, Tortoise Borrower LLC, a Delaware limited liability company ("Tortoise Borrower") and an affiliate of the Sponsor, purchased an aggregate of 6,660,183 warrants (the "Private Placement Warrants") at a purchase price of $1.00 per warrant, generating gross proceeds to the Company of approximately $6.66 million (the "Private Placement"). The Company intends to finance its Initial Business Combination with proceeds from the Initial Public Offering, the Private Placement, the private placement of Forward Purchase Securities (described in Note 5), and from additional issuances, if any, of the Company's capital stock, debt or a combination of the foregoing. *Trust Account* Upon the closing of the Initial Public Offering and the Private Placement, approximately $233.0 million was placed in a trust account (the "Trust Account"), with Continental Stock Transfer & Trust Company acting as trustee. The proceeds held in the Trust Account are invested only in U.S. government securities with a maturity of 180 days or less or in money market funds that meet certain conditions under Rule 2a-7 under the Investment Company Act of 1940, as amended, which invest only in direct U.S. government treasury obligations. Funds will remain in the Trust Account until the earlier of (i) the consummation of the Initial Business Combination and (ii) the distribution of the Trust Account proceeds as described below. The remaining proceeds outside the Trust Account may be used to pay for business, legal and accounting due diligence on prospective acquisitions and general and administrative expenses. The Company's amended and restated certificate of incorporation provides that, except for the withdrawal of interest to pay franchise and income taxes, none of the funds held in the Trust Account (including the interest earned on the funds in the Trust Account) will be released from the Trust Account until the earlier of: (i) the completion of the Initial Business Combination; (ii) the redemption of any shares of Class A common stock included in the Units sold in the Initial Public Offering (the "Public Shares") that have been properly tendered in connection with a stockholder vote seeking to amend the Company's amended and restated certificate of incorporation to affect the substance or timing of its obligation to redeem 100% of such Public Shares if it has not consummated an Initial Business Combination within 24 months from the closing of the Initial Public Offering (the "Combination Period"); and (iii) the redemption of 100% of the Public Shares if the Company is unable to complete an Initial Business Combination within the Combination Period. The proceeds deposited in the Trust Account could become subject to the claims of the Company's creditors, if any, which could have priority over the claims of the Company's public stockholders. *Initial Business Combination* The Company's management has broad discretion with respect to the specific application of the net proceeds of the Initial Public Offering, although substantially all of the net proceeds of the Initial Public Offering are intended to be generally applied toward consummating an Initial Business Combination. The New York Stock Exchange (the "NYSE") rules require that the Initial Business Combination occur with one or more target businesses that together have a fair market value of at least 80% of the assets held in the Trust Account (excluding the deferred underwriting discounts and commissions and taxes payable on the interest earned on the Trust Account) at the time of the agreement to enter into the Initial Business Combination. There is no assurance that the Company will be able to successfully effect an Initial Business Combination. The Company, after signing a definitive agreement for an Initial Business Combination, will either (i) seek stockholder approval of the Initial Business Combination at a meeting called for such purpose in connection with which stockholders may seek to redeem their Public Shares, regardless of whether they vote for or against the Initial Business Combination, for cash equal to their pro rata share of the aggregate amount on deposit in the Trust Account as of two business days prior to the consummation of the Initial Business Combination, including interest not previously released to the Company to pay its franchise and income taxes, or (ii) provide stockholders the opportunity to sell their Public Shares to the Company by means of a tender offer (and thereby avoid the need for a stockholder vote) for an amount in cash equal to their pro rata share of the aggregate amount on deposit in the Trust Account as of two business days prior to the consummation of the Initial Business Combination, including interest not previously released to the Company to pay its franchise and income taxes. The decision as to whether the Company will seek stockholder approval of the Initial Business Combination or allow stockholders to sell their Public Shares in a tender offer will be made by the Company, solely in its discretion, and will be based on a variety of factors such as the timing of the transaction and whether the terms of the transaction would otherwise require the Company to seek stockholder approval, unless a vote is required by law or under NYSE rules. If the Company seeks stockholder approval, it will complete its Initial Business Combination only if a majority of the outstanding shares of common stock voted are voted in favor of the Initial Business Combination. However, in no event will the Company redeem its Public Shares in an amount that would cause its net tangible assets to be less than $5,000,001. In such case, the Company would not proceed with the redemption of its Public Shares and the related Initial Business Combination, and instead would search for an alternate Initial Business Combination. If the Company holds a stockholder vote or there is a tender offer for shares in connection with an Initial Business Combination, a stockholder will have the right to redeem such holder's Public Shares for an amount in cash equal to such holder's pro rata share of the aggregate amount on deposit in the Trust Account as of two business days prior to the consummation of the Initial Business Combination, including interest not previously released to the Company to pay its franchise and income taxes. As a result, such Public Shares are recorded as temporary equity upon the completion of the Initial Public Offering, in accordance with the Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") 480, "Distinguishing Liabilities from Equity." Notwithstanding the foregoing, the Company's amended and restated certificate of incorporation provides that a public stockholder, together with any affiliate of such stockholder or any other person with whom such stockholder is acting in concert or as a "group" (as defined under Section 13 of the Securities Exchange Act of 1934, as amended (the "Exchange Act")), will be restricted from redeeming their shares with respect to more than an aggregate of 20% or more of the shares of Class A common stock sold in the Initial Public Offering, without the prior consent of the Company. The Sponsor, Tortoise Borrower, the Company's officers and directors and Atlas Point Energy Infrastructure Fund, LLC ("Atlas Point Fund") (collectively, the "Initial Stockholders") agreed not to propose an amendment to the amended and restated certificate of incorporation that would affect the substance or timing of the Company's obligation to redeem 100% of the Public Shares if the Company does not complete an Initial Business Combination, unless the Company provides the public stockholders the opportunity to redeem their shares of Class A common stock in conjunction with any such amendment. Pursuant to the Company's amended and restated certificate of incorporation, if the Company is unable to complete an Initial Business Combination within the Combination Period, the Company will (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible but no more than 10 business days thereafter subject to lawfully available funds therefor, redeem the Public Shares, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account including interest earned on the funds held in the Trust Account and not previously released to the Company to pay the Company's franchise and income taxes (less up to $100,000 of such net interest to pay dissolution expenses), divided by the number of then-outstanding Public Shares, which redemption will completely extinguish the public stockholders' rights as stockholders (including the right to receive further liquidating distributions, if any), subject to applicable law, and (iii) as promptly as reasonably possible following such redemption, subject to the approval of the Company's remaining stockholders and the Company's board of directors, dissolve and liquidate, subject in each case to the Company's obligations under Delaware law to provide for claims of creditors and the requirements of other applicable law. The Initial Stockholders have entered into a letter agreement with the Company, pursuant to which they agreed to waive their rights to liquidating distributions from the Trust Account with respect to any Founder Shares (as defined below) held by them if the Company fails to complete the Initial Business Combination within the Combination Period. However, if any of the Initial Stockholders acquire shares of Class A common stock in or after the Initial Public Offering, they will be entitled to liquidating distributions from the Trust Account with respect to such shares if the Company fails to complete the Initial Business Combination within the Combination Period. In the event of a liquidation, dissolution or winding up of the Company after an Initial Business Combination, the Company's stockholders are entitled to share ratably in all assets remaining available for distribution to them after payment of liabilities and after provision is made for each class of stock, if any, having preference over the common stock. The Company's stockholders have no preemptive or other subscription rights. There are no sinking fund provisions applicable to the common stock, except that the Company will provide its stockholders with the opportunity to redeem their Public Shares for cash equal to their pro rata share of the aggregate amount then on deposit in the Trust Account and not previously released to the Company to pay the Company's franchise and income taxes, upon the completion of the Initial Business Combination, subject to the limitations described herein. Commencing April 22, 2019, holders of the Units were permitted to elect to separately trade the shares of Class A common stock and Warrants (as defined below) included in the Units. No fractional shares will be issued upon separation of the Units and only whole Warrants will trade. *Going Concern Consideration* As of December 31, 2019, the Company had approximately $916,000 of cash in its operating account and approximately $3.0 million of investment income in the Trust Account available to pay franchise and income taxes (less up to $100,000 of such net interest to pay dissolution expenses). Through December 31, 2019, the Company's liquidity needs have been satisfied through a $25,000 capital contribution from the Sponsor in exchange for the issuance of the Founder Shares (as defined below and described in Note 4) to the Sponsor, an approximately $580,000 loan from the Sponsor pursuant to an unsecured promissory note (the "Note"), the net proceeds from the consummation of the Private Placement not held in the Trust Account and an aggregate of $812,000 of interest income released from the Trust Account since inception to fund tax obligations. The Company repaid the Note to the Sponsor in full on March 29, 2019. In connection with the Company's assessment of going concern considerations in accordance with FASB Accounting Standards Update ("ASU") 2014-15, "Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern," management has determined that the mandatory liquidation and subsequent dissolution raises substantial doubt about the Company's ability to continue as a going concern. No adjustments have been made to the carrying amounts of assets or liabilities should the Company be required to liquidate after March 4, 2021.

Description of Organization and Business Operations

12 Months Ended

Dec. 31, 2019

Description of Organization and Business Operations [Abstract]

DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS

NOTE 1. DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS

Organization and General

Tortoise Acquisition Corp. (the "Company") was incorporated in Delaware on November 7, 2018. The Company was formed for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses (the "Initial Business Combination"). The Company is an "emerging growth company," as defined in Section 2(a) of the Securities Act of 1933, as amended (the "Securities Act"), as modified by the Jumpstart Our Business Startups Act of 2012 (the "JOBS Act").

As of December 31, 2019, the Company had not commenced any operations. All activity for the period from November 7, 2018 (date of inception) to December 31, 2019 relates to the Company's formation and the initial public offering (the "Initial Public Offering") described below, and since the closing of the Initial Public Offering, the identification and evaluation of prospective acquisition targets for an Initial Business Combination and ongoing administrative and compliance matters. The Company will not generate any operating revenues until after completion of its Initial Business Combination, at the earliest. The Company generates non-operating income in the form of interest income earned on investments from the net proceeds derived from the Initial Public Offering.

Sponsor and Initial Public Offering

The Company's sponsor is Tortoise Sponsor LLC, a Delaware limited liability company (the "Sponsor"). As described in Note 3, on March 4, 2019, the Company consummated the Initial Public Offering of 23,300,917 of its units (the "Units"), including 800,917 Units that were issued pursuant to the underwriters' partial exercise of their over-allotment option, generating gross proceeds of approximately $233.0 million. As described in Note 4, on March 4, 2019, simultaneously with the closing of the Initial Public Offering, Tortoise Borrower LLC, a Delaware limited liability company ("Tortoise Borrower") and an affiliate of the Sponsor, purchased an aggregate of 6,660,183 warrants (the "Private Placement Warrants") at a purchase price of $1.00 per warrant, generating gross proceeds to the Company of approximately $6.66 million (the "Private Placement").

The Company intends to finance its Initial Business Combination with proceeds from the Initial Public Offering, the Private Placement, the private placement of Forward Purchase Securities (described in Note 5), and from additional issuances, if any, of the Company's capital stock, debt or a combination of the foregoing.

Trust Account

Upon the closing of the Initial Public Offering and the Private Placement, approximately $233.0 million was placed in a trust account (the "Trust Account"), with Continental Stock Transfer & Trust Company acting as trustee. The proceeds held in the Trust Account are invested only in U.S. government securities with a maturity of 180 days or less or in money market funds that meet certain conditions under Rule 2a-7 under the Investment Company Act of 1940, as amended, which invest only in direct U.S. government treasury obligations. Funds will remain in the Trust Account until the earlier of (i) the consummation of the Initial Business Combination and (ii) the distribution of the Trust Account proceeds as described below. The remaining proceeds outside the Trust Account may be used to pay for business, legal and accounting due diligence on prospective acquisitions and general and administrative expenses.

The Company's amended and restated certificate of incorporation provides that, except for the withdrawal of interest to pay franchise and income taxes, none of the funds held in the Trust Account (including the interest earned on the funds in the Trust Account) will be released from the Trust Account until the earlier of: (i) the completion of the Initial Business Combination; (ii) the redemption of any shares of Class A common stock included in the Units sold in the Initial Public Offering (the "Public Shares") that have been properly tendered in connection with a stockholder vote seeking to amend the Company's amended and restated certificate of incorporation to affect the substance or timing of its obligation to redeem 100% of such Public Shares if it has not consummated an Initial Business Combination within 24 months from the closing of the Initial Public Offering (the "Combination Period"); and (iii) the redemption of 100% of the Public Shares if the Company is unable to complete an Initial Business Combination within the Combination Period. The proceeds deposited in the Trust Account could become subject to the claims of the Company's creditors, if any, which could have priority over the claims of the Company's public stockholders.

Initial Business Combination

The Company's management has broad discretion with respect to the specific application of the net proceeds of the Initial Public Offering, although substantially all of the net proceeds of the Initial Public Offering are intended to be generally applied toward consummating an Initial Business Combination. The New York Stock Exchange (the "NYSE") rules require that the Initial Business Combination occur with one or more target businesses that together have a fair market value of at least 80% of the assets held in the Trust Account (excluding the deferred underwriting discounts and commissions and taxes payable on the interest earned on the Trust Account) at the time of the agreement to enter into the Initial Business Combination. There is no assurance that the Company will be able to successfully effect an Initial Business Combination.

The Company, after signing a definitive agreement for an Initial Business Combination, will either (i) seek stockholder approval of the Initial Business Combination at a meeting called for such purpose in connection with which stockholders may seek to redeem their Public Shares, regardless of whether they vote for or against the Initial Business Combination, for cash equal to their pro rata share of the aggregate amount on deposit in the Trust Account as of two business days prior to the consummation of the Initial Business Combination, including interest not previously released to the Company to pay its franchise and income taxes, or (ii) provide stockholders the opportunity to sell their Public Shares to the Company by means of a tender offer (and thereby avoid the need for a stockholder vote) for an amount in cash equal to their pro rata share of the aggregate amount on deposit in the Trust Account as of two business days prior to the consummation of the Initial Business Combination, including interest not previously released to the Company to pay its franchise and income taxes. The decision as to whether the Company will seek stockholder approval of the Initial Business Combination or allow stockholders to sell their Public Shares in a tender offer will be made by the Company, solely in its discretion, and will be based on a variety of factors such as the timing of the transaction and whether the terms of the transaction would otherwise require the Company to seek stockholder approval, unless a vote is required by law or under NYSE rules. If the Company seeks stockholder approval, it will complete its Initial Business Combination only if a majority of the outstanding shares of common stock voted are voted in favor of the Initial Business Combination. However, in no event will the Company redeem its Public Shares in an amount that would cause its net tangible assets to be less than $5,000,001. In such case, the Company would not proceed with the redemption of its Public Shares and the related Initial Business Combination, and instead would search for an alternate Initial Business Combination.

If the Company holds a stockholder vote or there is a tender offer for shares in connection with an Initial Business Combination, a stockholder will have the right to redeem such holder's Public Shares for an amount in cash equal to such holder's pro rata share of the aggregate amount on deposit in the Trust Account as of two business days prior to the consummation of the Initial Business Combination, including interest not previously released to the Company to pay its franchise and income taxes. As a result, such Public Shares are recorded as temporary equity upon the completion of the Initial Public Offering, in accordance with the Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") 480, "Distinguishing Liabilities from Equity."

Notwithstanding the foregoing, the Company's amended and restated certificate of incorporation provides that a public stockholder, together with any affiliate of such stockholder or any other person with whom such stockholder is acting in concert or as a "group" (as defined under Section 13 of the Securities Exchange Act of 1934, as amended (the "Exchange Act")), will be restricted from redeeming their shares with respect to more than an aggregate of 20% or more of the shares of Class A common stock sold in the Initial Public Offering, without the prior consent of the Company.

The Sponsor, Tortoise Borrower, the Company's officers and directors and Atlas Point Energy Infrastructure Fund, LLC ("Atlas Point Fund") (collectively, the "Initial Stockholders") agreed not to propose an amendment to the amended and restated certificate of incorporation that would affect the substance or timing of the Company's obligation to redeem 100% of the Public Shares if the Company does not complete an Initial Business Combination, unless the Company provides the public stockholders the opportunity to redeem their shares of Class A common stock in conjunction with any such amendment.

Pursuant to the Company's amended and restated certificate of incorporation, if the Company is unable to complete an Initial Business Combination within the Combination Period, the Company will (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible but no more than 10 business days thereafter subject to lawfully available funds therefor, redeem the Public Shares, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account including interest earned on the funds held in the Trust Account and not previously released to the Company to pay the Company's franchise and income taxes (less up to $100,000 of such net interest to pay dissolution expenses), divided by the number of then-outstanding Public Shares, which redemption will completely extinguish the public stockholders' rights as stockholders (including the right to receive further liquidating distributions, if any), subject to applicable law, and (iii) as promptly as reasonably possible following such redemption, subject to the approval of the Company's remaining stockholders and the Company's board of directors, dissolve and liquidate, subject in each case to the Company's obligations under Delaware law to provide for claims of creditors and the requirements of other applicable law. The Initial Stockholders have entered into a letter agreement with the Company, pursuant to which they agreed to waive their rights to liquidating distributions from the Trust Account with respect to any Founder Shares (as defined below) held by them if the Company fails to complete the Initial Business Combination within the Combination Period. However, if any of the Initial Stockholders acquire shares of Class A common stock in or after the Initial Public Offering, they will be entitled to liquidating distributions from the Trust Account with respect to such shares if the Company fails to complete the Initial Business Combination within the Combination Period.

In the event of a liquidation, dissolution or winding up of the Company after an Initial Business Combination, the Company's stockholders are entitled to share ratably in all assets remaining available for distribution to them after payment of liabilities and after provision is made for each class of stock, if any, having preference over the common stock. The Company's stockholders have no preemptive or other subscription rights. There are no sinking fund provisions applicable to the common stock, except that the Company will provide its stockholders with the opportunity to redeem their Public Shares for cash equal to their pro rata share of the aggregate amount then on deposit in the Trust Account and not previously released to the Company to pay the Company's franchise and income taxes, upon the completion of the Initial Business Combination, subject to the limitations described herein.

Commencing April 22, 2019, holders of the Units were permitted to elect to separately trade the shares of Class A common stock and Warrants (as defined below) included in the Units. No fractional shares will be issued upon separation of the Units and only whole Warrants will trade.

Going Concern Consideration

As of December 31, 2019, the Company had approximately $916,000 of cash in its operating account and approximately $3.0 million of investment income in the Trust Account available to pay franchise and income taxes (less up to $100,000 of such net interest to pay dissolution expenses).

Through December 31, 2019, the Company's liquidity needs have been satisfied through a $25,000 capital contribution from the Sponsor in exchange for the issuance of the Founder Shares (as defined below and described in Note 4) to the Sponsor, an approximately $580,000 loan from the Sponsor pursuant to an unsecured promissory note (the "Note"), the net proceeds from the consummation of the Private Placement not held in the Trust Account and an aggregate of $812,000 of interest income released from the Trust Account since inception to fund tax obligations. The Company repaid the Note to the Sponsor in full on March 29, 2019.

In connection with the Company's assessment of going concern considerations in accordance with FASB Accounting Standards Update ("ASU") 2014-15, "Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern," management has determined that the mandatory liquidation and subsequent dissolution raises substantial doubt about the Company's ability to continue as a going concern. No adjustments have been made to the carrying amounts of assets or liabilities should the Company be required to liquidate after March 4, 2021.