Benefit Plans and Other Postretirement Benefits (Details) $ in Thousands		1 Months Ended	3 Months Ended
		Jan. 31, 2019 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Jan. 01, 2019 Plan
Pension Plan [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost			$ 1,100	$ 1,200
Interest cost	[1]		1,400	1,400
Expected return on plan assets	[1]		(2,100)	(2,300)
Amortization of prior service cost (credit)	[1]		0	0
Amortization of net loss	[1]		1,100	1,400
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement			0	0
Defined Benefit Plan Net Benefit Cost (Credit) Recognized Before Regulatory Adjustments			1,500	1,700
Defined Benefit Plan Credits Not Recognized Due To Effects of Regulation			200	200
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)			1,700	1,900
Total contributions to the pension plans during the period		$ 7,000
Other Postretirement Benefits Plan [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost			0	0
Interest cost	[1]		100	200
Expected return on plan assets	[1]		0	0
Amortization of prior service cost (credit)	[1]		(100)	(100)
Amortization of net loss	[1]		100	100
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement			0	0
Defined Benefit Plan Net Benefit Cost (Credit) Recognized Before Regulatory Adjustments			100	200
Defined Benefit Plan Credits Not Recognized Due To Effects of Regulation			0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)			$ 100	$ 200
Xcel Energy Inc. | Pension Plan [Member]
Components of Net Periodic Benefit Cost [Abstract]
Total contributions to the pension plans during the period		$ 150,000
Number of Xcel Energy's pension plans to which contributions were made | Plan					4

[1] The 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.