Benefit Plans and Other Postretirement Benefits, Pension Benefits (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018 USD ($) Plan	Dec. 31, 2017 USD ($) Plan	Dec. 31, 2016 USD ($) Plan
Pension Plan [Member]
Pension Benefits [Abstract]
Total benefit obligation		$ 477.8	$ 515.9	$ 483.6
Net benefit cost recognized for financial reporting		$ 14.8	$ 14.9	$ 17.4
Minimum number of years historical achieved weighted average annual returns used to determine investment return assumptions (in years)		20 years
Expected average long-term rate of return on assets (as a percent)		6.78%	6.78%	6.78%
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)		100.00%	100.00%
Pension Plan [Member] | Domestic and international equity securities
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)		35.00%	34.00%
Pension Plan [Member] | Long-Duration Fixed Income and Long-duration fixed income and interest rate swap securities
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)		32.00%	31.00%
Pension Plan [Member] | Short-to-intermediate fixed income securities
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)		16.00%	19.00%
Pension Plan [Member] | Alternative investments
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)		15.00%	14.00%
Pension Plan [Member] | Cash
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)		2.00%	2.00%
Supplemental Executive Retirement Plan (SERP) and Nonqualified Pension Plan
Pension Benefits [Abstract]
Total benefit obligation		$ 2.0
Net benefit cost recognized for financial reporting		4.0	$ 5.0
Parent Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to postretirement health care plans during 2019		11.0
Target Pension Asset Allocations [Abstract]
Total contributions to Xcel Energy's postretirement health care plans during the year		$ 11.0	$ 20.0	$ 18.0
Parent Company [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan number of pension plans to which contributions were made | Plan		4	4	4
Parent Company [Member] | Supplemental Executive Retirement Plan (SERP) and Nonqualified Pension Plan
Pension Benefits [Abstract]
Total benefit obligation		$ 33.0	$ 37.0
Scenario, Forecast [Member] | Pension Plan [Member]
Pension Benefits [Abstract]
Expected average long-term rate of return on assets for next fiscal year (as a percent)	6.78%