Benefit Plans and Other Postretirement Benefits (Details) (USD $)	1 Months Ended	3 Months Ended		6 Months Ended
	Jan. 31, 2013 Plan	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Pension Benefits
Components of Net Periodic Benefit Cost [Abstract]
Service cost		$ 24,070,000	$ 21,853,000	$ 48,141,000	$ 43,182,000
Interest cost		35,173,000	39,365,000	70,345,000	78,088,000
Expected return on plan assets		(49,613,000)	(52,072,000)	(99,226,000)	(103,548,000)
Amortization of transition obligation		0	0	0	0
Amortization of prior service cost (credit)		1,468,000	5,267,000	2,936,000	10,533,000
Amortization of net loss		36,038,000	27,467,000	72,076,000	53,785,000
Net periodic benefit cost		47,136,000	41,880,000	94,272,000	82,040,000
Costs not recognized and additional cost recognized due to the effects of regulation		(7,089,000)	(10,158,000)	(14,936,000)	(19,291,000)
Net benefit cost recognized for financial reporting		40,047,000	31,722,000	79,336,000	62,749,000
Total contributions to Xcel Energy's pension plans during the period	191,500,000
Number of pension plans to which contributions were made	4
Postretirement Health Care Benefits
Components of Net Periodic Benefit Cost [Abstract]
Service cost		1,182,000	922,000	2,364,000	2,102,000
Interest cost		8,417,000	9,551,000	16,834,000	18,931,000
Expected return on plan assets		(8,253,000)	(7,094,000)	(16,506,000)	(14,205,000)
Amortization of transition obligation		206,000	3,580,000	412,000	7,160,000
Amortization of prior service cost (credit)		(2,438,000)	(1,888,000)	(4,876,000)	(3,776,000)
Amortization of net loss		5,646,000	4,487,000	11,292,000	8,452,000
Net periodic benefit cost		4,760,000	9,558,000	9,520,000	18,664,000
Costs not recognized and additional cost recognized due to the effects of regulation		0	973,000	0	1,946,000
Net benefit cost recognized for financial reporting		$ 4,760,000	$ 10,531,000	$ 9,520,000	$ 20,610,000