The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 25
-Paragraph 4
-URI https://asc.fasb.org/extlink&oid=116646717&loc=d3e6290-110844

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

Name:	us-gaap_AssetRetirementObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Plant Wansley (Details) - USD ($)	Dec. 31, 2022	Sep. 30, 2022	Jul. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Asset Retirement Obligation [Line Items]
Cost to close plant	$ 1,343,743,000			$ 1,287,143,000	$ 1,135,983,000
Plant Wansley
Asset Retirement Obligation [Line Items]
Ownership interest (as a percent)			30.00%
Cost to close plant		$ 40,656,000