Benefit Plans and Other Postretirement Benefits (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2016 USD ($) Plan	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)
Pension Benefits
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		$ 2,440	$ 2,752	$ 7,320	$ 8,255
Interest cost		5,315	5,046	15,945	15,138
Expected return on plan assets		(6,901)	(7,153)	(20,703)	(21,458)
Amortization of prior service cost (credit)		0	9	0	29
Amortization of net loss (gain)		2,997	3,772	8,991	11,316
Net periodic benefit cost (credit)		3,851	4,426	11,553	13,280
Defined Benefit Plan Credits Recognized Due To Effects of Regulation		637	740	1,353	2,139
Net benefit cost (credit) recognized for financial reporting		4,488	5,166	12,906	15,419
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	582	716
Interest cost		455	436	1,365	1,309
Expected return on plan assets		(594)	(635)	(1,782)	(1,905)
Amortization of prior service cost (credit)		(100)	(101)	(300)	(301)
Amortization of net loss (gain)		(146)	(159)	(438)	(479)
Net periodic benefit cost (credit)		(191)	(220)	(573)	(660)
Defined Benefit Plan Credits Recognized Due To Effects of Regulation		0	0	0	0
Net benefit cost (credit) recognized for financial reporting		$ (191)	$ (220)	$ (573)	$ (660)
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