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		$ 6,302,000	$ 5,497,000
Interest cost		11,540,000	12,624,000
Expected return on plan assets		(15,955,000)	(16,235,000)
Amortization of transition obligation		0	0
Amortization of prior service (credit) cost		(266,000)	57,000
Amortization of net loss		10,854,000	8,305,000
Net periodic benefit cost		12,475,000	10,248,000
Additional cost recognized due to the effects of regulation		0	0
Net benefit cost recognized for financial reporting		12,475,000	10,248,000
Total contributions to Xcel Energy's pension plans during the period	44,300,000
Postretirement Health Care Benefits [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost		803,000	823,000
Interest cost		5,934,000	6,142,000
Expected return on plan assets		(7,307,000)	(6,270,000)
Amortization of transition obligation		196,000	2,751,000
Amortization of prior service (credit) cost		(1,229,000)	(1,288,000)
Amortization of net loss		3,490,000	2,604,000
Net periodic benefit cost		1,887,000	4,762,000
Additional cost recognized due to the effects of regulation		0	973,000
Net benefit cost recognized for financial reporting		1,887,000	5,735,000
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