Benefit Plans and Other Postretirement Benefits (Details) $ in Thousands	1 Months Ended	3 Months Ended
	Jan. 31, 2016 USD ($) Plan	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)
Pension Benefits
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		$ 2,440	$ 2,752
Interest cost		5,315	5,046
Expected return on plan assets		(6,901)	(7,153)
Amortization of prior service cost (credit)		0	10
Amortization of net loss (gain)		2,997	3,772
Net periodic benefit cost (credit)		3,851	4,427
Defined Benefit Plan Regulatory Adjustments		78	713
Net benefit cost (credit) recognized for financial reporting		3,929	5,140
Total contributions to the pension plans during the period	$ 18,000
Postretirement Health Care Benefits
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		194	239
Interest cost		455	436
Expected return on plan assets		(594)	(635)
Amortization of prior service cost (credit)		(100)	(100)
Amortization of net loss (gain)		(146)	(160)
Net periodic benefit cost (credit)		(191)	(220)
Defined Benefit Plan Regulatory Adjustments		0	0
Net benefit cost (credit) recognized for financial reporting		$ (191)	$ (220)
Xcel Energy Inc. | Pension Benefits
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Total contributions to the pension plans during the period	$ 125,000
Number of Xcel Energy's pension plans to which contributions were made | Plan	4