Employee Benefit Plans 5 (Details) - Pension Benefits - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee benefit plans
Regulatory adjustment	$ 483	$ 593	$ 0
GSWC
Employee benefit plans
Regulatory adjustment	483	(593)	1,700
Bear Valley Electric Service, Inc.
Employee benefit plans
Regulatory adjustment	$ 200	$ 205	$ 271

The increase (decrease) during the reporting period in the value of other assets that are created when regulatory agencies permits public utilities to defer costs to the balance sheet.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Name:	us-gaap_IncreaseDecreaseInOtherRegulatoryAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration