Dividend Limitations (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Dividend limitations
Common shareholder’s equity	$ 709,549	$ 685,947	$ 641,673	$ 601,530
Subsidiaries
Dividend limitations
Dividends paid	56,400	38,300	47,300
GSWC
Dividend limitations
Dividends paid	27,000	38,300	22,500
Common shareholder’s equity	$ 643,906	615,686	583,298	551,188
Ratio of Indebtedness to Net Capital	0.4568
GSWC | Maximum
Dividend limitations
Ratio of Indebtedness to Net Capital	0.6667
Earnings Reinvested in the Business
Dividend limitations
Common shareholder’s equity	$ 449,391	427,505	385,007	345,964
Earnings Reinvested in the Business | GSWC
Dividend limitations
Common shareholder’s equity	$ 285,783	$ 259,156	$ 228,392	$ 257,434