XML 49 R39.htm IDEA: XBRL DOCUMENT
v3.23.3

Basis of Presentation and Significant Accounting Policies - Narrative (Details) $ / shares in Units, $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2023 USD ($) tranche $ / shares shares | Sep. 30, 2023 USD ($) trading_day segment tranche line_of_business $ / shares shares | Dec. 31, 2022 USD ($)
Class of Stock [Line Items] |  |  |
Number of operating segments | segment |  | 1 |
Number of reportable segments | segment |  | 1 |
Number of line of businesses | line_of_business |  | 1 |
Cash deposits, amounts in excess of FDIC limit | $ | $ 544,727 | $ 544,727 | $ 4,644
Maturity of time deposits | 6 months | 6 months |
Tax receivable agreement, net cash savings, percentage | 0.75 | 0.75 |
Useful Life | 20 years | 20 years |
Demonstration Plant |  |  |
Class of Stock [Line Items] |  |  |
Useful Life | 7 years | 7 years |
OpCo |  |  |
Class of Stock [Line Items] |  |  |
Subsidiary, ownership percentage | 32.60% | 32.60% |
Price Based Lockup Shares |  |  |
Class of Stock [Line Items] |  |  |
Lockup shares, transfer threshold |  | 3 years |
Time-Based Lockup Shares |  |  |
Class of Stock [Line Items] |  |  |
Lockup shares, transfer threshold |  | 1 year |
Price Based Lockup Shares, Transfer Tranche One | Price Based Lockup Shares |  |  |
Class of Stock [Line Items] |  |  |
Lockup shares, percentage of shares transferable | 0.33 | 0.33 |
Price Based Lockup Shares, Transfer Tranche Two | Price Based Lockup Shares |  |  |
Class of Stock [Line Items] |  |  |
Lockup shares, percentage of shares transferable | 0.33 | 0.33 |
Price Based Lockup Shares, Transfer Tranche Three | Price Based Lockup Shares |  |  |
Class of Stock [Line Items] |  |  |
Lockup shares, percentage of shares transferable | 1 | 1 |
NCI Holders | OpCo |  |  |
Class of Stock [Line Items] |  |  |
Noncontrolling interest, ownership percentage | 67.40% | 67.40% |
Class A Common Stock |  |  |
Class of Stock [Line Items] |  |  |
Common stock subject to vesting and transfer restrictions (in shares) | shares | 986,775 | 986,775 |
Number of tranches | tranche | 3 | 3 |
Class A Common Stock | Price Based Lockup Shares |  |  |
Class of Stock [Line Items] |  |  |
Common stock, lockup shares (in shares) | shares | 44,544,551 | 44,544,551 |
Lockup shares, threshold trading days |  | 20 |
Lockup shares, threshold consecutive trading days |  | 30 |
Class A Common Stock | Time-Based Lockup Shares |  |  |
Class of Stock [Line Items] |  |  |
Common stock, lockup shares (in shares) | shares | 89,449,655 | 89,449,655 |
Lockup shares, threshold trading days |  | 20 |
Lockup shares, threshold consecutive trading days |  | 30 |
Share price (in usd per share) | $ / shares | $ 12.00 | $ 12.00 |
Class A Common Stock | Price Based Lockup Shares, Transfer Tranche One | Price Based Lockup Shares |  |  |
Class of Stock [Line Items] |  |  |
Share price (in usd per share) | $ / shares | 12.00 | 12.00 |
Class A Common Stock | Price Based Lockup Shares, Transfer Tranche Two | Price Based Lockup Shares |  |  |
Class of Stock [Line Items] |  |  |
Share price (in usd per share) | $ / shares | 14.00 | 14.00 |
Class A Common Stock | Price Based Lockup Shares, Transfer Tranche Three | Price Based Lockup Shares |  |  |
Class of Stock [Line Items] |  |  |
Share price (in usd per share) | $ / shares | 16.00 | 16.00 |
Class A Common Stock | Earnout Shares Vesting, Tranche One |  |  |
Class of Stock [Line Items] |  |  |
Volume weighted average stock price trigger (in usd per share) | $ / shares | 12.00 | $ 12.00 |
Earnout shares vesting, threshold trading days |  | 20 |
Earnout shares vesting, threshold consecutive trading days |  | 30 |
Class A Common Stock | Earnout Shares Vesting, Tranche Two |  |  |
Class of Stock [Line Items] |  |  |
Volume weighted average stock price trigger (in usd per share) | $ / shares | $ 14.00 | $ 14.00 |
Earnout shares vesting, threshold trading days |  | 20 |
Earnout shares vesting, threshold consecutive trading days |  | 30 |
Class A Common Stock | Earnout Shares Vesting, Tranche Three |  |  |
Class of Stock [Line Items] |  |  |
Volume weighted average stock price trigger (in usd per share) | $ / shares |  | $ 16.00 |
Earnout shares vesting, threshold trading days |  | 20 |
Earnout shares vesting, threshold consecutive trading days |  | 30 |
Earnout shares, term |  | 3 years |
Class A Common Stock | OpCo |  |  |
Class of Stock [Line Items] |  |  |
Common stock subject to vesting and transfer restrictions (in shares) | shares | 128,908,518 | 128,908,518 |
Class A Common Stock | NET Power, Inc. |  |  |
Class of Stock [Line Items] |  |  |
Common stock subject to vesting and transfer restrictions (in shares) | shares | 54,047,495 | 54,047,495 |
Class B ordinary shares |  |  |
Class of Stock [Line Items] |  |  |
Common stock subject to vesting and transfer restrictions (in shares) | shares | 6,072,463 | 6,072,463 |
Class B ordinary shares | Price Based Lockup Shares |  |  |
Class of Stock [Line Items] |  |  |
Common stock, lockup shares (in shares) | shares | 1,575,045 | 1,575,045 |
Class B ordinary shares | Time-Based Lockup Shares |  |  |
Class of Stock [Line Items] |  |  |
Common stock, lockup shares (in shares) | shares | 3,510,643 | 3,510,643 |
Class B ordinary shares | OpCo |  |  |
Class of Stock [Line Items] |  |  |
Common stock subject to vesting and transfer restrictions (in shares) | shares | 7,624,999 | 7,624,999 |

X
- Definition Cash Deposits, Amounts In Excess Of FDIC Limit + References No definition available. + Details
Name: | npwr_CashDepositsAmountsInExcessOfFDICLimit
Namespace Prefix: | npwr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Common Stock, Lockup Shares + References No definition available. + Details
Name: | npwr_CommonStockLockupShares
Namespace Prefix: | npwr_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common Stock, Shares, Subject To Vesting And Transfer Restrictions + References No definition available. + Details
Name: | npwr_CommonStockSharesSubjectToVestingAndTransferRestrictions
Namespace Prefix: | npwr_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Earnout Shares, Term + References No definition available. + Details
Name: | npwr_EarnoutSharesTerm
Namespace Prefix: | npwr_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Earnout Shares Vesting, Threshold Consecutive Trading Days + References No definition available. + Details
Name: | npwr_EarnoutSharesVestingThresholdConsecutiveTradingDays
Namespace Prefix: | npwr_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Earnout Shares Vesting, Threshold Trading Days + References No definition available. + Details
Name: | npwr_EarnoutSharesVestingThresholdTradingDays
Namespace Prefix: | npwr_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Price Based Lockup Shares, Shares Transferable, Percentage + References No definition available. + Details
Name: | npwr_LockupSharesSharesTransferablePercentage
Namespace Prefix: | npwr_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Lockup Shares, Threshold Consecutive Trading Days + References No definition available. + Details
Name: | npwr_LockupSharesThresholdConsecutiveTradingDays
Namespace Prefix: | npwr_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Lockup Shares, Threshold Trading Days + References No definition available. + Details
Name: | npwr_LockupSharesThresholdTradingDays
Namespace Prefix: | npwr_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Lockup Shares, Transfer Threshold + References No definition available. + Details
Name: | npwr_LockupSharesTransferThreshold
Namespace Prefix: | npwr_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number Of Line Of Businesses + References No definition available. + Details
Name: | npwr_NumberOfLineOfBusinesses
Namespace Prefix: | npwr_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number Of Tranches + References No definition available. + Details
Name: | npwr_NumberOfTranches
Namespace Prefix: | npwr_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tax Receivable Agreement, Net Cash Savings, Percentage + References No definition available. + Details
Name: | npwr_TaxReceivableAgreementNetCashSavingsPercentage
Namespace Prefix: | npwr_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Volume Weighted Average Stock Price Trigger + References No definition available. + Details
Name: | npwr_VolumeWeightedAverageStockPriceTrigger
Namespace Prefix: | npwr_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481112/505-10-50-13 Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef -Topic 272 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483014/272-10-45-3 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 272 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482987/272-10-50-1 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(d)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481112/505-10-50-13 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481112/505-10-50-13 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481112/505-10-50-13 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (h) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481112/505-10-50-13 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 14 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481112/505-10-50-14 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 18 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481112/505-10-50-18 Reference 11: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(27)(b)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 Reference 12: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 Reference 13: http://www.xbrl.org/2003/role/disclosureRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481112/505-10-50-2 Reference 14: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 Reference 15: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 3 -Subparagraph (SX 210.6-03(i)(2)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479886/946-10-S99-3 Reference 16: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 3 -Subparagraph (SX 210.6-03(i)(1)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479886/946-10-S99-3 Reference 17: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 3 -Subparagraph (SX 210.6-03(i)(2)(i)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479886/946-10-S99-3 Reference 18: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 3 -Subparagraph (SX 210.6-03(i)(2)(ii)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479886/946-10-S99-3 + Details
Name: | us-gaap_ClassOfStockLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Period of time between issuance and maturity of customer deposits, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Industry Guide -Number 3 -Section V -Paragraph D-E -Publisher SEC + Details
Name: | us-gaap_MaturityOfTimeDeposits
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity. + References No definition available. + Details
Name: | us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The parent entity's interest in net assets of the subsidiary, expressed as a percentage. + References No definition available. + Details
Name: | us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 18 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482810/280-10-50-18 + Details
Name: | us-gaap_NumberOfOperatingSegments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 18 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482810/280-10-50-18 + Details
Name: | us-gaap_NumberOfReportableSegments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
Name: | us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Price of a single share of a number of saleable stocks of a company. + References No definition available. + Details
Name: | us-gaap_SharePrice
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_OwnershipAxis=npwr_OpCoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | npwr_LockupSharesProgramAxis=npwr_PriceBasedLockupSharesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | npwr_LockupSharesProgramAxis=npwr_TimeBasedLockupSharesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | npwr_LockupSharesTransfersAxis=npwr_LockupSharesTransferTrancheOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | npwr_LockupSharesTransfersAxis=npwr_LockupSharesTransferTrancheTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | npwr_LockupSharesTransfersAxis=npwr_LockupSharesTransferTrancheThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=npwr_NCIHoldersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_CommonClassAMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VestingAxis=npwr_EarnoutSharesVestingTrancheOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VestingAxis=npwr_EarnoutSharesVestingTrancheTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VestingAxis=npwr_EarnoutSharesVestingTrancheThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=npwr_OpCoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=npwr_NETPowerIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_CommonClassBMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |