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		$ 6,466	$ 7,065
Interest cost		13,849	12,714
Expected return on plan assets		(17,692)	(18,148)
Amortization of prior service credit		(807)	(784)
Amortization of net loss		6,693	9,094
Net periodic benefit cost (credit)		8,509	9,941
Costs not recognized due to the effects of regulation		766	(366)
Net benefit cost (credit) recognized for financial reporting		9,275	9,575
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	232
Interest cost		4,518	4,375
Expected return on plan assets		(5,575)	(5,951)
Amortization of prior service credit		(1,562)	(1,562)
Amortization of net loss		483	619
Net periodic benefit cost (credit)		(1,944)	(2,287)
Costs not recognized due to the effects of regulation		0	0
Net benefit cost (credit) recognized for financial reporting		$ (1,944)	$ (2,287)
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