Funded Status (Details) - USD ($) $ in Millions	1 Months Ended		12 Months Ended
	Jan. 31, 2020		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Plan Assets, Payment for Settlement			$ 20		$ 198
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Settlement Charge Recognized in Operating and Maintenance Expenses			2,338		2,352		$ 2,270
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated Benefit Obligation at Dec. 31			3,465		3,275
Change in Projected Benefit Obligation [Roll Forward]
Obligation at Jan. 1	$ 3,701		3,477		3,828
Service cost			86		94		94
Interest cost			145		133		147
Plan amendments			1		0
Actuarial loss			273		(224)
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant			0		0
Defined Benefit Plan, Benefit Obligation, Prescription Drug Subsidy Receipt			0		0
Benefit payments			(281)		(354)
Obligation at Dec. 31			3,701		3,477		3,828
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	3,184	[1]	2,742	[1]	3,088
Actual return (loss) on plan assets			568		(142)
Employer contributions			155		150
Benefit payments			(281)		(354)
Fair value of plan assets at Dec. 31			3,184	[1]	2,742	[1]	3,088
Funded Status of Plans at Dec. 31 [Abstract]
Funded status			(517)		(735)
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost [Abstract]
Net loss			1,447		1,633
Prior service (credit) cost			(15)		(20)
Total			1,432		1,613
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates [Abstract]
Current regulatory assets			78		94
Noncurrent regulatory assets			1,285		1,446
Deferred income taxes			18		19
Net-of-tax accumulated other comprehensive income			51		54
Total			$ 1,432		$ 1,613
Significant Assumptions Used to Measure Benefit Obligations [Abstract]
Discount rate for year-end valuation (as a percent)			3.49%		4.31%
Expected average long-term increase in compensation level (as a percent)			3.75%		3.75%
Cash Flows [Abstract]
Total contributions to Xcel Energy's pension plans during the period			$ 154		$ 150		162
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost			86		94		94
Interest cost			145		133		147
Expected return on plan assets			(203)		(209)		(209)
Amortization of prior service cost (credit)			(5)		(5)		(2)
Amortization of net loss			87		111		107
Settlement charge			6		91		81
Net periodic benefit cost			116		215		218
Costs not recognized due to regulation			(1)		(75)		(79)
Net benefit cost recognized for financial reporting			115		140		$ 139
Settlement Charge Recognized in Operating and Maintenance Expenses			$ 1		$ 11
Significant Assumptions Used to Measure Costs [Abstract]
Discount rate (as a percent)			4.31%		3.63%		4.13%
Expected average long-term increase in compensation level (as a percent)			3.75%		3.75%		3.75%
Expected average long-term rate of return on assets (as a percent)			6.87%		6.87%		6.87%
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant			$ 0		$ 0
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Recorded As Current Regulatory Liabilities			0		0
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Recorded As Noncurrent Regulatory Liabilities			0		0
Other Postretirement Benefits Plan [Member]
Change in Projected Benefit Obligation [Roll Forward]
Obligation at Jan. 1	547		542		621
Service cost			2		2		$ 2
Interest cost			22		22		24
Plan amendments			0		0
Actuarial loss			19		(62)
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant			8		8
Defined Benefit Plan, Benefit Obligation, Prescription Drug Subsidy Receipt			1		1
Benefit payments			(47)		(50)
Obligation at Dec. 31			547		542		621
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	449	[2]	417	[2]	461
Actual return (loss) on plan assets			56		(13)
Employer contributions			15		11
Benefit payments			(47)		(50)
Fair value of plan assets at Dec. 31			449	[2]	417	[2]	461
Funded Status of Plans at Dec. 31 [Abstract]
Funded status			(98)		(125)
Assets for Plan Benefits, Defined Benefit Plan			21
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost [Abstract]
Net loss			95		116
Prior service (credit) cost			(23)		(33)
Total			72		83
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates [Abstract]
Current regulatory assets			0		0
Noncurrent regulatory assets			80		89
Deferred income taxes			1		1
Net-of-tax accumulated other comprehensive income			4		4
Total			$ 72		$ 83
Significant Assumptions Used to Measure Benefit Obligations [Abstract]
Discount rate for year-end valuation (as a percent)			3.47%		4.32%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Pre-65			6.00%		6.50%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Post-65			5.10%		5.30%
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost			$ 2		$ 2		2
Interest cost			22		22		24
Expected return on plan assets			(21)		(26)		(25)
Amortization of prior service cost (credit)			(10)		(11)		(11)
Amortization of net loss			5		8		7
Settlement charge			0		0		0
Net periodic benefit cost			(2)		(5)		(3)
Costs not recognized due to regulation			1		2		0
Net benefit cost recognized for financial reporting			$ (1)		$ (3)		$ (3)
Significant Assumptions Used to Measure Costs [Abstract]
Discount rate (as a percent)			4.32%		3.62%		4.13%
Expected average long-term increase in compensation level (as a percent)			0.00%		0.00%		0.00%
Expected average long-term rate of return on assets (as a percent)			4.50%		5.30%		5.80%
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant			$ 8		$ 8
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Recorded As Current Regulatory Liabilities			1		1
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Recorded As Noncurrent Regulatory Liabilities			$ 12		$ 10
Ultimate health care trend assumption rate (as a percent)			4.50%		4.50%
Period until ultimate trend rate is reached (in years)			3 years		4 years
Subsequent Event | Pension Plan [Member]
Cash Flows [Abstract]
Total contributions to Xcel Energy's pension plans during the period	$ 150

[1] ^(a)  See Note 10 for further information regarding fair value measurement inputs and methods.

[2] ^(a)  See Note 10 for further information on fair value measurement inputs and methods.