v3.26.1
Fair Value Measurements (Details) - EBP 008 - USD ($)
Dec. 31, 2025
Dec. 31, 2024
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value $ 414,761,087 $ 339,127,494
Fair Value, Inputs, Level 1, Level 2, and Level 3    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 63,313,234 53,555,615
Fair Value, Inputs, Level 1, Level 2, and Level 3 | NW Natural Holding Company unitized stock    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 12,236,653 10,360,750
Fair Value, Inputs, Level 1, Level 2, and Level 3 | Mutual funds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 40,446,472 35,737,764
Fair Value, Inputs, Level 1, Level 2, and Level 3 | Brokerage accounts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 10,630,109 7,457,101
Level 1    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 63,313,234 53,555,615
Level 1 | NW Natural Holding Company unitized stock    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 12,236,653 10,360,750
Level 1 | Mutual funds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 40,446,472 35,737,764
Level 1 | Brokerage accounts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 10,630,109 7,457,101
Level 1 | Common Collective Trust    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 2    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 2 | NW Natural Holding Company unitized stock    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 2 | Mutual funds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 2 | Brokerage accounts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 2 | Common Collective Trust    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 3    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 3 | NW Natural Holding Company unitized stock    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 3 | Mutual funds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 3 | Brokerage accounts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 3 | Common Collective Trust    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
NAV    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 351,447,853 285,571,879
NAV | Common Collective Trust    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value $ 351,447,853 $ 285,571,879