Revenues (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022		Sep. 30, 2023	Sep. 30, 2022
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,591	$ 1,844		$ 4,556	$ 5,044
Regulated Electric | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	1,513	1,730		3,958	4,308
Regulated Natural Gas | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	65	102		563	703
All Other | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	13	12		35	33
Retail
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,185	1,257		3,421	3,641
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	484	488		1,427	1,483
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	690	757		1,963	2,115
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	11	12		31	43
Retail | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,118	1,165	[1]	2,870	2,961
Retail | Regulated Electric | Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	445	441		1,120	1,116
Retail | Regulated Electric | C&I
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	664	714		1,724	1,816
Retail | Regulated Electric | Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	9	10		26	29
Retail | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	54	80		516	647
Retail | Regulated Natural Gas | Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	28	37		277	348
Retail | Regulated Natural Gas | C&I
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	26	43		239	299
Retail | Regulated Natural Gas | Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0		0	0
Retail | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	13	12		35	33
Retail | All Other | Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	11	10		30	19
Retail | All Other | C&I
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0		0	0
Retail | All Other | Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2	2		5	14
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	103	242		287	505
Wholesale | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	103	242	[1]	287	505
Wholesale | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0		0	0
Wholesale | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0		0	0
Transmission
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	72	101		202	225
Transmission | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	72	101	[1]	202	225
Transmission | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0		0	0
Transmission | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0		0	0
Interchange
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	134	150
Interchange | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	130	140	[1]
Interchange | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	4	10
Interchange | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer				373	418
Other | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer				364	403
Other | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer				9	15
Other | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer				0	0
Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,494	1,750		4,283	4,789
Total revenue from contracts with customers | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,423	1,648		3,723	4,094
Total revenue from contracts with customers | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	58	90		525	662
Total revenue from contracts with customers | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	13	12		35	33
Alternative revenue and other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	97	94		273	255
Alternative revenue and other | Regulated Electric
Disaggregation of Revenue [Line Items]
Alternative revenue and other	90	82		235	214
Alternative revenue and other | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Alternative revenue and other	7	12		38	41
Alternative revenue and other | All Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 0	$ 0		$ 0	$ 0

[1] In the third quarter of 2022, as a result of lump-sum distributions during the 2022 plan year, NSP-Minnesota recorded a pension settlement charge of $29 million, which was not recognized in earnings due to the effects of rate making.