CONSOLIDATED STATEMENTS OF CHANGES IN COMMON SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	GSWC	Common Stock	Common Stock GSWC	Earnings Reinvested in the Business	Earnings Reinvested in the Business GSWC
Beginning Balance (in shares) at Dec. 31, 2021			36,936,000	170.0000
Beginning Balance at Dec. 31, 2021	$ 685,947	$ 615,686	$ 258,442	$ 356,530	$ 427,505	$ 259,156
Add:
Net Income	$ 78,396	$ 53,770			78,396	53,770
Issuance of Common Shares from an at-the-market program, net of issuance costs (in Shares)	25,956	0
Issuances of Common Shares under stock-based compensation plans ( in shares)			26,000
Issuances of Common Shares under stock-based compensation plans	$ 0		$ 0
Stock-based compensation, net of taxes paid from shares withheld from employees related to net share settlements	1,562	$ 1,450	1,562	1,450
Dividend equivalent rights on stock-based awards not paid in cash	154	143	$ 154	$ 143
Deduct:
Dividends on Common Shares	56,356	27,000			56,356	27,000
Dividend equivalent rights on stock-based awards	154	143			154	143
Ending Balance (in shares) at Dec. 31, 2022			36,962,000	170.0000
Ending Balance at Dec. 31, 2022	709,549	643,906	$ 260,158	$ 358,123	449,391	285,783
Add:
Net Income	$ 124,921	$ 102,708			124,921	102,708
Issuance of Common Shares from an at-the-market program, net of issuance costs (in Shares)	18,371	1		1.0000
Issuance of Common Shares from an at-the-market program, net of issuance costs		$ 10,000		$ 10,000
Issuances of Common Shares under stock-based compensation plans ( in shares)			19,000
Issuances of Common Shares under stock-based compensation plans	$ 0		$ 0
Stock-based compensation, net of taxes paid from shares withheld from employees related to net share settlements	2,834	2,614	2,834	2,614
Dividend equivalent rights on stock-based awards not paid in cash	187	172	$ 187	$ 172
Deduct:
Dividends on Common Shares	61,195	55,400			61,195	55,400
Dividend equivalent rights on stock-based awards	$ 187	$ 172			187	172
Ending Balance (in shares) at Dec. 31, 2023	36,980,612	171.0000	36,981,000	171.0000
Ending Balance at Dec. 31, 2023	$ 776,109	$ 703,828	$ 263,179	$ 370,909	512,930	332,919
Add:
Net Income	$ 119,268	$ 94,463			119,268	94,463
Issuance of Common Shares from an at-the-market program, net of issuance costs (in Shares)	25,196	2.7586	1,145,000	2.7586
Issuance of Common Shares from an at-the-market program, net of issuance costs	$ 88,661	$ 40,000	$ 88,661
Issuances of Common Shares under stock-based compensation plans ( in shares)			25,000
Issuances of Common Shares under stock-based compensation plans	0		$ 0
Stock-based compensation, net of taxes paid from shares withheld from employees related to net share settlements	3,030	2,642	3,030	$ 2,642
Dividend equivalent rights on stock-based awards not paid in cash	273	246	$ 273	$ 246
Deduct:
Dividends on Common Shares	67,017	35,100			67,017	35,100
Dividend equivalent rights on stock-based awards	$ 273	$ 246			273	246
Ending Balance (in shares) at Dec. 31, 2024	38,151,027	173.7586	38,151,000	173.7586
Ending Balance at Dec. 31, 2024	$ 920,051	$ 805,833	$ 355,143	$ 413,797	$ 564,908	$ 392,036