Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2025 USD ($) mi	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Summary Of Accounting Policies [Line Items]
Number of Months to Establish ROU Asset and Liability	12 months
Number of Utilities that do not have cost recovery mechanism	1
Maturity Period To Be Considered Cash Equivalents	3 months
Contributions or Advances in Aid of Construction	$ 7.8	$ 5.9
Net property, plant and equipment	3,118.4	2,735.9
Accumulated depreciation	637.6	567.6
Depreciation and accretion reported in operations expenses	15.9	15.8	$ 11.9
Operating Lease, Right-of-Use Asset	9.9	10.5
Total Operating and Finance Lease Liabilities	(10.0)	(11.0)
Jointly Owned Pipeline [Member]
Summary Of Accounting Policies [Line Items]
Net property, plant and equipment	28.4
Accumulated Depreciation, Depletion and Amortization, Sale or Disposal of Property, Plant and Equipment	$ 3.5	$ 2.8
Natural Gas Operations
Summary Of Accounting Policies [Line Items]
Length of pipeline | mi	26
Minimum [Member]
Summary Of Accounting Policies [Line Items]
Operating Lease, Liability	$ 11.0
Maximum
Summary Of Accounting Policies [Line Items]
Operating Lease, Liability	$ 13.0