Regulatory matters - IPUC (Details) - Natural gas distribution - IPUC - Intermountain Gas Company - USD ($) $ in Millions	Oct. 20, 2025	May 30, 2025
Public Utilities, General Disclosures [Line Items]
Public utilities, requested rate increase (decrease), amount		$ 26.5
Public utilities, requested rate increase (decrease), percentage		8.60%
Subsequent Event
Public Utilities, General Disclosures [Line Items]
Public utilities, requested rate increase (decrease), percentage	4.20%
Public utilities, annual revenue increase (decrease)	$ 13.0