Long-Term Debt (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024	Feb. 12, 2025 USD ($)	Jun. 05, 2024 USD ($)	Jan. 13, 2023 USD ($)
Debt Instrument [Line Items]
Ratio of Indebtedness to EBITDA	8
GSWC
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 130.0
Ratio of indebtedness to net capital	0.4754
Ratio of Indebtedness to EBITDA	3.8
GSWC | Maximum
Debt Instrument [Line Items]
Ratio of indebtedness to net capital	0.6667
Series A Senior Notes 5.12 Percent Due 2033 | GSWC
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 100.0
Interest rate per annum (as a percent)				5.12%
Interest rate (as a percent)				5.12%
Private Placement Notes | GSWC
Debt Instrument [Line Items]
Debt Instrument Redemption Premium above Treasury Yield	50.00%
Series A Senior Notes 5.22 Percent Due 2038 | GSWC
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 30.0
Interest rate per annum (as a percent)				5.22%
Interest rate (as a percent)				5.22%
Unsecured Private Placement Notes | GSWC
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 65.0	$ 130.0
Interest rate per annum (as a percent)			5.50%
Interest rate (as a percent)			5.50%
Debt due Feb 2030 | BVES | Subsequent Event
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 50.0
Interest rate per annum (as a percent)		6.12%
Interest rate (as a percent)		6.12%