Regulatory assets (Details) - USD ($)		9 Months Ended
	Oct. 19, 2022	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Feb. 28, 2021
Regulatory Assets
Regulatory Assets, Current		$ 148,160,000	$ 118,691,000	$ 133,135,000
Regulatory Assets, Noncurrent		344,442,000	357,851,000	379,245,000
Total regulatory assets		492,602,000	476,542,000	512,380,000
Regulatory assets not earning a rate of return		264,400,000	296,600,000	318,200,000
Gas Distribution [Member] | MNPUC [Member] | Subsequent Event [Member] | Great Plains Natural Gas Co. [Member]
Regulatory Assets
Disallowed Gas Costs	$ (845,000)
Natural gas costs recoverable through rate adjustments
Regulatory Assets
Regulatory Assets, Current		112,079,000	86,371,000	98,211,000
Regulatory Assets, Noncurrent		$ 462,000	5,186,000	6,084,000
Total regulatory assets					$ 44,000,000
Natural gas costs recoverable through rate adjustments | Minimum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 1 year
Natural gas costs recoverable through rate adjustments | Maximum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 2 years
Conservation programs
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 1 year
Regulatory Assets, Current		$ 9,363,000	8,225,000	8,495,000
Decoupling
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 1 year
Regulatory Assets, Current		$ 6,549,000	9,131,000	7,195,000
Cost recovery mechanisms
Regulatory Assets
Regulatory Assets, Current		3,354,000	4,536,000	4,693,000
Regulatory Assets, Noncurrent		$ 67,094,000	44,870,000	43,955,000
Cost recovery mechanisms | Minimum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 1 year
Cost recovery mechanisms | Maximum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 10 years
Other regulatory assets
Regulatory Assets
Regulatory Assets, Current		$ 16,815,000	10,428,000	14,541,000
Regulatory Assets, Noncurrent		$ 10,931,000	9,742,000	9,856,000
Other regulatory assets | Minimum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 1 year
Other regulatory assets | Maximum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 17 years
Pension and postretirement benefits
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		**
Regulatory Assets, Noncurrent		$ 137,582,000	142,681,000	155,888,000
Plant costs/asset retirement obligations
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Over plant lives
Regulatory Assets, Noncurrent		$ 61,941,000	63,116,000	73,528,000
Plant to be retired
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		-
Regulatory Assets, Noncurrent		$ 24,740,000	50,070,000	48,544,000
Manufactured gas plant site remediation
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		-
Regulatory Assets, Noncurrent		$ 25,963,000	26,053,000	26,000,000
Taxes recoverable from customers
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Over plant lives
Regulatory Assets, Noncurrent		$ 12,394,000	12,339,000	11,438,000
Long-term debt refinancing costs
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 38 years
Regulatory Assets, Noncurrent		$ 3,335,000	$ 3,794,000	$ 3,952,000