Benefit Plans and Other Postretirement Benefits (Details) $ in Millions			1 Months Ended	3 Months Ended		6 Months Ended
		Jul. 01, 2019 USD ($)	Jan. 31, 2019 USD ($) Plan	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)
Pension Plan [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost				$ 22	$ 24	$ 43	$ 47
Interest cost (a)	[1]			36	33	72	67
Expected return on plan assets (a)	[1]			(51)	(52)	(102)	(104)
Amortization of prior service credit (a)	[1]			(1)	(1)	(2)	(2)
Amortization of net loss (a)	[1]			22	27	44	55
Net periodic benefit cost (credit)				28	31	55	63
Defined Benefit Plan Credits Not Recognized Due To Effects of Regulation				1		2
Credits (costs) not recognized due to the effects of regulation					1		2
Net benefit cost (credit) recognized for financial reporting				29	30	57	61
Total contributions to Xcel Energy's pension plans during the period			$ 150
Number of pension plans to which contributions were made | Plan			4
Other Postretirement Benefits Plan [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost				0	1	1	1
Interest cost (a)	[1]			6	5	11	11
Expected return on plan assets (a)	[1]			(5)	(6)	(11)	(13)
Amortization of prior service credit (a)	[1]			(3)	(3)	(5)	(5)
Amortization of net loss (a)	[1]			1	2	3	3
Net periodic benefit cost (credit)				(1)	(1)	(1)	(3)
Defined Benefit Plan Credits Not Recognized Due To Effects of Regulation						1
Credits (costs) not recognized due to the effects of regulation				0	0		0
Net benefit cost (credit) recognized for financial reporting				$ (1)	$ (1)	$ 0	$ (3)
Parent Company | Pension Plan [Member]
Components of Net Periodic Benefit Cost [Abstract]
Total contributions to Xcel Energy's pension plans during the period		$ 4

[1] Components of net periodic cost other than the service cost component are included in the line item “other expense, net” in the consolidated statement of income or capitalized on the consolidated balance sheet as a regulatory asset.