Benefit Plans and Other Postretirement Benefits (Details) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2014 Plan	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Pension Benefits
Components of Net Periodic Benefit Cost [Abstract]
Service cost		$ 22,086,000	$ 24,071,000	$ 66,257,000	$ 72,212,000
Interest cost		39,155,000	35,173,000	117,465,000	105,518,000
Expected return on plan assets		(51,801,000)	(49,613,000)	(155,403,000)	(148,839,000)
Amortization of transition obligation		0	0	0	0
Amortization of prior service (credit) cost		(437,000)	1,468,000	(1,310,000)	4,404,000
Amortization of net loss		29,191,000	36,038,000	87,572,000	108,114,000
Net periodic benefit cost		38,194,000	47,137,000	114,581,000	141,409,000
Costs not recognized due to the effects of regulation		(6,605,000)	(12,986,000)	(20,261,000)	(27,922,000)
Net benefit cost recognized for financial reporting		31,589,000	34,151,000	94,320,000	113,487,000
Total contributions to Xcel Energy's pension plans during the period	130,000,000
Number of pension plans to which contributions were made	3
Postretirement Health Care Benefits
Components of Net Periodic Benefit Cost [Abstract]
Service cost		864,000	1,182,000	2,592,000	3,546,000
Interest cost		8,507,000	8,417,000	25,521,000	25,251,000
Expected return on plan assets		(8,489,000)	(8,253,000)	(25,466,000)	(24,759,000)
Amortization of transition obligation		0	206,000	0	618,000
Amortization of prior service (credit) cost		(2,672,000)	(2,438,000)	(8,016,000)	(7,314,000)
Amortization of net loss		2,935,000	5,646,000	8,805,000	16,938,000
Net periodic benefit cost		1,145,000	4,760,000	3,436,000	14,280,000
Costs not recognized due to the effects of regulation		0	0	0	0
Net benefit cost recognized for financial reporting		$ 1,145,000	$ 4,760,000	$ 3,436,000	$ 14,280,000