Benefit Plans and Other Postretirement Benefits (Details) (USD $)	1 Months Ended	3 Months Ended
	Jan. 31, 2013	Mar. 31, 2013	Mar. 31, 2012
Pension Benefits [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost		$ 2,404,000	$ 2,133,000
Interest cost		4,477,000	4,880,000
Expected return on plan assets		(5,993,000)	(6,247,000)
Amortization of transition obligation		0	0
Amortization of prior service cost (credit)		218,000	360,000
Amortization of net loss (gain)		4,287,000	3,142,000
Net periodic benefit cost		5,393,000	4,268,000
Costs not recognized and additional cost recognized due to the effects of regulation		(1,075,000)	(1,075,000)
Net benefit cost recognized for financial reporting		4,318,000	3,193,000
Total contributions to Xcel Energy's pension plans during the period	21,900,000
Postretirement Health Care Benefits [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost		342,000	328,000
Interest cost		588,000	671,000
Expected return on plan assets		(796,000)	(677,000)
Amortization of transition obligation		0	386,000
Amortization of prior service cost (credit)		(121,000)	(37,000)
Amortization of net loss (gain)		(2,000)	283,000
Net periodic benefit cost		11,000	954,000
Costs not recognized and additional cost recognized due to the effects of regulation		0	0
Net benefit cost recognized for financial reporting		11,000	954,000
Xcel Energy Inc. [Member] | Pension Benefits [Member]
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