Benefit Plans and Other Postretirement Benefits (Details) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2014	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Pension Benefits
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		$ 2,296,000	$ 2,404,000	$ 6,888,000	$ 7,211,000
Interest cost		5,111,000	4,477,000	15,333,000	13,431,000
Expected return on plan assets		(6,545,000)	(5,993,000)	(19,635,000)	(17,978,000)
Amortization of prior service cost (credit)		14,000	218,000	41,000	653,000
Amortization of net loss (gain)		3,332,000	4,287,000	9,995,000	12,861,000
Net periodic benefit cost (credit)		4,208,000	5,393,000	12,622,000	16,178,000
Credits recognized (costs not recognized) due to the effects of regulation		707,000	62,000	2,122,000	(1,330,000)
Net benefit cost (credit) recognized for financial reporting		4,915,000	5,455,000	14,744,000	14,848,000
Total contributions to the pension plans during the period	4,400,000
Postretirement Health Care Benefits
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		312,000	342,000	935,000	1,026,000
Interest cost		643,000	588,000	1,929,000	1,764,000
Expected return on plan assets		(812,000)	(796,000)	(2,435,000)	(2,388,000)
Amortization of prior service cost (credit)		(100,000)	(121,000)	(301,000)	(363,000)
Amortization of net loss (gain)		(80,000)	(2,000)	(241,000)	(5,000)
Net periodic benefit cost (credit)		(37,000)	11,000	(113,000)	34,000
Credits recognized (costs not recognized) due to the effects of regulation		0	0	0	0
Net benefit cost (credit) recognized for financial reporting		(37,000)	11,000	(113,000)	34,000
Xcel Energy Inc. | Pension Benefits
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Total contributions to the pension plans during the period	$ 130,000,000
Number of Xcel Energy's pension plans to which contributions were made	3