Benefit Plans and Other Postretirement Benefits, Projected Benefit Payments (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Defined Contribution Plan, Administrative Expense		$ 12	$ 11	$ 11
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Gross Projected Benefit Payments [Abstract]
2020		31
2021		31
2022		30
2023		30
2024		29
2025-2029		130
Expected Medicare Part D Subsidies [Abstract]
2020		2
2021		2
2022		2
2023		2
2023		2
2025-2029		12
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
2020		29
2021		29
2022		28
2023		28
2024		27
2025-2029		118
Pension Plan [Member]
Defined Benefit Plan, Gross Projected Benefit Payments [Abstract]
2020		83
2021		83
2022		82
2023		82
2024		82
2025-2029		393
Pension Plan [Member] | Xcel Energy [Member]
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Total contributions to Xcel Energy's pension plans during the period		150	154	150
Pension Plan [Member] | Xcel Energy [Member] | Subsequent Event
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Total contributions to Xcel Energy's pension plans during the period	$ 125
Pension Plan [Member] | PSCo [Member]
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Total contributions to Xcel Energy's pension plans during the period		50	46	22
Pension Plan [Member] | PSCo [Member] | Subsequent Event
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Total contributions to Xcel Energy's pension plans during the period	45
Defined Benefit Plan, Overfunded Plan [Member] | Xcel Energy [Member]
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Total contributions to Xcel Energy's pension plans during the period		11	15	11
Defined Benefit Plan, Overfunded Plan [Member] | Xcel Energy [Member] | Subsequent Event
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Total contributions to Xcel Energy's pension plans during the period	$ 10
Defined Benefit Plan, Overfunded Plan [Member] | PSCo [Member]
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Total contributions to Xcel Energy's pension plans during the period		$ 3	$ 4	$ 5