Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Reclassification within Operating Revenues [Member]		$ 1,700	$ 2,200
Public Utility, Property, Plant and Equipment [Line Items]
Regulatory debits	$ 1,436	1,148	1,107
Regulatory Assets	1,358	21,434
Regulatory Liabilities	388,465	358,957
Capitalized Interest Costs, Including Allowance for Funds Used During Construction [Abstract]
Allowance for funds used during construction, debt	200	300	700
Allowance for funds used during construction, equity	1,400	400	2,700
Interest Payments [Abstract]
Cash payments for interest, net of interest capitalized	26,100	26,100	26,200
Other Regulatory Assets (Liabilities) [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Regulatory Liabilities	26,700	22,000
Levelized depreciation
Public Utility, Property, Plant and Equipment [Line Items]
Regulatory debits	1,400	1,100	$ 1,100
Asset Retirement Obligation
Public Utility, Property, Plant and Equipment [Line Items]
Regulatory Assets	$ 102,100	$ 96,300
Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	1 year
Minimum [Member] | Storage Facilities
Public Utility, Property, Plant and Equipment [Line Items]
Depreciaton rates	1.60%	1.60%	1.60%
Minimum [Member] | Transmission Facilities [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Depreciaton rates	2.80%	2.80%	2.80%
Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	30 years
Maximum [Member] | Storage Facilities
Public Utility, Property, Plant and Equipment [Line Items]
Depreciaton rates	2.76%	2.76%	2.76%
Maximum [Member] | Transmission Facilities [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Depreciaton rates	6.97%	6.97%	6.97%