Benefit Plans and Other Postretirement Benefits (Details) (USD $)	1 Months Ended	3 Months Ended		6 Months Ended
	Jan. 31, 2014	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Pension Benefits
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		$ 5,985,000	$ 6,301,000	$ 11,970,000	$ 12,603,000
Interest cost		13,319,000	11,540,000	26,638,000	23,080,000
Expected return on plan assets		(17,677,000)	(15,955,000)	(35,354,000)	(31,910,000)
Amortization of transition obligation		0	0	0	0
Amortization of prior service credit		(773,000)	(266,000)	(1,546,000)	(532,000)
Amortization of net loss		8,473,000	10,854,000	16,946,000	21,708,000
Net benefit cost (credit) recognized for financial reporting		9,327,000	12,474,000	18,654,000	24,949,000
Total contributions to the pension plans during the period	35,100,000
Postretirement Health Care Benefits
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		478,000	803,000	957,000	1,606,000
Interest cost		5,926,000	5,934,000	11,852,000	11,868,000
Expected return on plan assets		(7,553,000)	(7,307,000)	(15,107,000)	(14,614,000)
Amortization of transition obligation		0	196,000	0	392,000
Amortization of prior service credit		(1,561,000)	(1,229,000)	(3,123,000)	(2,458,000)
Amortization of net loss		1,608,000	3,489,000	3,217,000	6,979,000
Net benefit cost (credit) recognized for financial reporting		(1,102,000)	1,886,000	(2,204,000)	3,773,000
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