CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Property, Plant and Equipment
Regulated utility plant, at cost	$ 2,988,225	$ 2,899,564
Non-utility property, at cost	51,934	50,422
Total	3,040,159	2,949,986
Less - accumulated depreciation	(672,940)	(653,667)
Net property, plant and equipment	2,367,219	2,296,319
Property, Plant, and Equipment, Other, after Accumulated Depreciation [Abstract]
Other property and investments	61,612	58,664
Current Assets
Cash and cash equivalents	21,657	18,824
Accounts receivable - customers, less allowance for doubtful accounts	41,668	38,321
Unbilled receivable	30,122	26,621
Receivable from the U.S. government (Note 2)	38,576	46,400
Other accounts receivable, less allowance for doubtful accounts	7,441	6,127
Income taxes receivable	1,747	0
Materials and supplies	18,550	16,406
Regulatory assets — current	24,903	39,396
Prepayments and other current assets	12,086	7,551
Contract assets (Note 2)	29,744	31,428
Total current assets	226,494	231,074
Other Assets
Unbilled revenue — receivable from the U.S. government (Note 2)	664	1,258
Receivable from the U.S. government (Note 2)	24,814	27,660
Contract assets (Note 2)	228	79
Operating lease right-of-use assets	7,166	6,093
Regulatory assets	23,045	30,073
Other	63,718	63,872
Total other assets	119,635	129,035
Total Assets	2,774,960	2,715,092
Capitalization
Common shares, no par value	467,473	425,153
Retained earnings	654,007	620,428
Total common shareholders’ equity	1,121,480	1,045,581
Long-term debt	717,735	782,700
Total capitalization	1,839,215	1,828,281
Current Liabilities
Long-term debt — current	73,227	8,209
Accounts payable	79,507	86,021
Income taxes payable	0	1,169
Accrued other taxes	14,780	12,871
Accrued employee expenses	14,164	16,193
Accrued interest	9,525	9,545
Contract liabilities (Note 2)	10,679	11,735
Operating lease liabilities	2,341	2,062
Purchase power contract derivative at fair value (Note 5)	14,631	15,503
Other	12,252	11,304
Total current liabilities	231,106	174,612
Other Credits
Notes payable to banks	119,000	141,000
Advances for construction	80,926	77,976
Contributions in aid of construction – net	182,369	179,277
Deferred income taxes	199,215	194,121
Regulatory liabilities	61,919	60,205
Unamortized investment tax credits	839	873
Accrued pension and other postretirement benefits	37,073	36,557
Operating lease liabilities	5,191	4,406
Other	18,107	17,784
Total other credits	704,639	712,199
Commitments and Contingencies (Note 9)
Total Capitalization and Liabilities	2,774,960	2,715,092
GSWC
Property, Plant and Equipment
Total	2,729,607	2,648,213
Less - accumulated depreciation	(580,728)	(564,529)
Net property, plant and equipment	2,148,879	2,083,684
Property, Plant, and Equipment, Other, after Accumulated Depreciation [Abstract]
Other property and investments	58,783	55,829
Current Assets
Cash and cash equivalents	8,916	9,964
Accounts receivable - customers, less allowance for doubtful accounts	37,246	33,212
Unbilled receivable	25,628	20,607
Other accounts receivable, less allowance for doubtful accounts	6,145	2,767
Income taxes receivable	2,648	2,555
Materials and supplies	9,024	9,127
Regulatory assets — current	8,256	23,211
Prepayments and other current assets	8,704	6,365
Total current assets	107,121	109,251
Other Assets
Operating lease right-of-use assets	6,978	5,856
Other	61,204	61,242
Total other assets	68,182	67,098
Total Assets	2,382,965	2,315,862
Capitalization
Common shares, no par value	480,797	478,494
Retained earnings	481,392	455,243
Total common shareholders’ equity	962,189	933,737
Long-term debt	633,060	698,060
Total capitalization	1,595,249	1,631,797
Current Liabilities
Long-term debt — current	73,227	8,209
Accounts payable	65,416	67,426
Accrued other taxes	12,571	10,322
Accrued employee expenses	11,023	12,847
Accrued interest	7,807	7,738
Operating lease liabilities	2,244	1,967
Other	11,574	10,762
Total current liabilities	183,862	119,271
Other Credits
Notes payable to banks	38,000	13,000
Advances for construction	80,906	77,956
Contributions in aid of construction – net	182,369	179,277
Deferred income taxes	182,791	177,291
Regulatory liabilities	61,919	60,205
Unamortized investment tax credits	839	873
Accrued pension and other postretirement benefits	36,389	35,948
Operating lease liabilities	5,104	4,268
Other	15,537	15,976
Total other credits	603,854	564,794
Commitments and Contingencies (Note 9)
Total Capitalization and Liabilities	2,382,965	2,315,862
GSWC | Related Party
Current Assets
Receivable from affiliate	$ 554	$ 1,443