Fair Value of Financial Instruments - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Mutual Funds \| Fair Value, Inputs, Level 1
Fair value of financial instruments
Long-term debt-GSWC	$ 29.2	$ 27.5

Includes other investments and securities that are not at fair value as of the balance sheet date and those that are not accounted for under the equity method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(5))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(12))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant