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 [Abstract]
Service cost		$ 1,104	$ 1,190
Interest cost		1,704	1,630
Expected return on plan assets		(2,289)	(2,371)
Amortization of prior service cost (credit)		28	28
Amortization of net loss		1,348	1,701
Net benefit cost recognized for financial reporting		1,895	2,178
Total contributions to the pension plans during the period	$ 7,400
Postretirement Health Care Benefits
Components of Net Periodic Benefit Cost [Abstract]
Service cost		6	7
Interest cost		163	163
Expected return on plan assets		(6)	(8)
Amortization of prior service cost (credit)		(88)	(88)
Amortization of net loss		83	114
Net benefit cost recognized for financial reporting		$ 158	$ 188
Xcel Energy Inc. | Pension Benefits
Components of Net Periodic Benefit Cost [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