Segment Information - Capital Expenditure by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 29, 2026	Mar. 30, 2025
Segment Reporting Information [Line Items]
Consolidated capital expenditures	$ 20,234	$ 24,362
Operating Segments \| U.S. Gas
Segment Reporting Information [Line Items]
Consolidated capital expenditures	5,744	10,188
Operating Segments \| Canadian Operations
Segment Reporting Information [Line Items]
Consolidated capital expenditures	2,315	622
Operating Segments \| Union Electric
Segment Reporting Information [Line Items]
Consolidated capital expenditures	9,801	3,705
Operating Segments \| Non-Union Electric
Segment Reporting Information [Line Items]
Consolidated capital expenditures	2,119	9,845
Other
Segment Reporting Information [Line Items]
Consolidated capital expenditures	$ 255	$ 2

Amount of expenditure for addition to long-lived assets included in determination of segment assets by chief operating decision maker (CODM) or otherwise regularly provided to CODM. Excludes expenditure for addition to financial instrument, long-term customer relationship of financial institution, mortgage and other servicing rights, deferred policy acquisition cost, and deferred tax assets.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
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-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 270
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-Topic 280
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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