Benefit Plans and Other Postretirement Benefits (Details) (USD $)	1 Months Ended	3 Months Ended		6 Months Ended
	Jan. 31, 2013	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Pension Benefits
Components of Net Periodic Benefit Cost [Abstract]
Service cost		$ 2,403,000	$ 2,127,000	$ 4,807,000	$ 4,260,000
Interest cost		4,477,000	4,920,000	8,954,000	9,800,000
Expected return on plan assets		(5,992,000)	(6,217,000)	(11,985,000)	(12,464,000)
Amortization of transition obligation		0	0	0	0
Amortization of prior service cost (credit)		217,000	359,000	435,000	719,000
Amortization of net loss (gain)		4,287,000	3,265,000	8,574,000	6,407,000
Net periodic benefit cost		5,392,000	4,454,000	10,785,000	8,722,000
Costs not recognized due to the effects of regulation		(317,000)	(1,075,000)	(1,392,000)	(2,150,000)
Net benefit cost recognized for financial reporting		5,075,000	3,379,000	9,393,000	6,572,000
Total contributions to Xcel Energy's pension plans during the period	21,900,000
Postretirement Health Care Benefits
Components of Net Periodic Benefit Cost [Abstract]
Service cost		342,000	302,000	684,000	630,000
Interest cost		588,000	745,000	1,176,000	1,416,000
Expected return on plan assets		(796,000)	(674,000)	(1,592,000)	(1,351,000)
Amortization of transition obligation		0	387,000	0	773,000
Amortization of prior service cost (credit)		(121,000)	(37,000)	(242,000)	(74,000)
Amortization of net loss (gain)		(1,000)	345,000	(3,000)	628,000
Net periodic benefit cost		12,000	1,068,000	23,000	2,022,000
Costs not recognized due to the effects of regulation		0	0	0	0
Net benefit cost recognized for financial reporting		12,000	1,068,000	23,000	2,022,000
Xcel Energy Inc. | Pension Benefits
Components of Net Periodic Benefit Cost [Abstract]
Total contributions to Xcel Energy's pension plans during the period	$ 191,500,000
Number of Xcel Energy's pension plans to which contributions were made	4