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		$ 6,820	$ 6,466
Interest cost		12,640	13,849
Expected return on plan assets		(17,134)	(17,692)
Amortization of prior service credit		(803)	(807)
Amortization of net loss		7,089	6,693
Net periodic benefit cost (credit)		8,612	8,509
Credits not recognized due to the effects of regulation		736	766
Net benefit cost (credit) recognized for financial reporting		9,348	9,275
Total contributions to the pension plans during the period	$ 16,800
Postretirement Health Care Benefits
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		192	192
Interest cost		4,191	4,518
Expected return on plan assets		(5,476)	(5,575)
Amortization of prior service credit		(1,562)	(1,562)
Amortization of net loss		961	483
Net periodic benefit cost (credit)		(1,694)	(1,944)
Credits not recognized due to the effects of regulation		0	0
Net benefit cost (credit) recognized for financial reporting		$ (1,694)	$ (1,944)
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