Benefit Plans and Other Postretirement Benefits (Details) (USD $)	1 Months Ended	3 Months Ended
	Jan. 31, 2015	Mar. 31, 2015	Mar. 31, 2014
Pension Benefits
Components of Net Periodic Benefit Cost [Abstract]
Service cost		$ 1,190,000	$ 1,132,000
Interest cost		1,630,000	1,814,000
Expected return on plan assets		(2,371,000)	(2,411,000)
Amortization of prior service cost (credit)		28,000	28,000
Amortization of net loss		1,701,000	1,654,000
Net benefit cost recognized for financial reporting		2,178,000	2,217,000
Total contributions to the pension plans during the period	4,900,000
Postretirement Health Care Benefits
Components of Net Periodic Benefit Cost [Abstract]
Service cost		7,000	9,000
Interest cost		163,000	198,000
Expected return on plan assets		(8,000)	(13,000)
Amortization of prior service cost (credit)		(88,000)	(88,000)
Amortization of net loss		114,000	167,000
Net benefit cost recognized for financial reporting		188,000	273,000
Xcel Energy Inc. | Pension Benefits
Components of Net Periodic Benefit Cost [Abstract]
Total contributions to the pension plans during the period	$ 90,000,000
Number of Xcel Energy's pension plans to which contributions were made	4