Benefit Plans and Other Postretirement Benefits (Details) $ in Thousands	1 Months Ended	3 Months Ended
	Jan. 31, 2017 USD ($) Plan	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)
Pension Benefits
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		$ 2,440	$ 2,440
Interest cost		4,928	5,315
Expected return on plan assets		(6,971)	(6,901)
Amortization of prior service cost (credit)		0	0
Amortization of net loss (gain)		3,245	2,997
Net periodic benefit cost (credit)		3,642	3,851
Defined Benefit Plan Credits Recognized Due To Effects of Regulation		148	78
Net benefit cost (credit) recognized for financial reporting		3,790	3,929
Total contributions to the pension plans during the period	$ 23,000
Postretirement Health Care Benefits
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		219	194
Interest cost		415	455
Expected return on plan assets		(589)	(594)
Amortization of prior service cost (credit)		(100)	(100)
Amortization of net loss (gain)		(155)	(146)
Net periodic benefit cost (credit)		(210)	(191)
Defined Benefit Plan Credits Recognized Due To Effects of Regulation		0	0
Net benefit cost (credit) recognized for financial reporting		$ (210)	$ (191)
Xcel Energy Inc. | Pension Benefits
Components of Net Periodic Benefit Cost (Credit) [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