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v3.25.2

Non-controlling Interest - Narrative (Details) | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024
Equity [Abstract] |  |  |  |
Non-controlling interest holders | 64.40% | 66.20% | 64.40% | 66.20%

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- Definition Redeemable Noncontrolling Interest, Percentage Of Common Units + References No definition available. + Details
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Namespace Prefix: | npwr_
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Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration