Winter Storm Uri (Details) - USD ($)	1 Months Ended
	Feb. 28, 2021	Mar. 31, 2022	Sep. 30, 2021	Sep. 14, 2021	Jul. 30, 2021	Mar. 31, 2021
Unusual or Infrequent Item, or Both [Line Items]
Aggregate natural gas purchases	$ 2,300,000,000
Regulatory assets		$ 2,475,545,000	$ 2,521,441,000
Winter Storm Uri incremental costs
Unusual or Infrequent Item, or Both [Line Items]
Regulatory assets		2,106,521,000	$ 2,100,728,000
Winter Storm Uri incremental costs | Winter Storm Uri
Unusual or Infrequent Item, or Both [Line Items]
Regulatory assets		2,100,000,000
Winter Storm Uri incremental costs | Kansas | Winter Storm Uri
Unusual or Infrequent Item, or Both [Line Items]
Regulatory assets		87,900,000
Winter Storm Uri incremental costs | Texas | Winter Storm Uri
Unusual or Infrequent Item, or Both [Line Items]
Regulatory assets		$ 2,018,600,000
Extraordinary Gas Cost | Kansas | Winter Storm Uri
Unusual or Infrequent Item, or Both [Line Items]
Regulatory assets				$ 94,100,000
Extraordinary Gas Cost | Texas | Winter Storm Uri
Unusual or Infrequent Item, or Both [Line Items]
Regulatory assets					$ 2,000,000,000
Senior Notes Due 2023
Unusual or Infrequent Item, or Both [Line Items]
Debt instrument, face amount						$ 2,200,000,000
Senior Notes Due 2023 | Texas
Unusual or Infrequent Item, or Both [Line Items]
Debt instrument, face amount						2,200,000,000
Other administrative costs						$ 600,000