Benefit Plans and Other Postretirement Benefits (Details) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2014	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Pension Benefits
Components of Net Periodic Benefit Cost [Abstract]
Service cost		$ 1,132,000	$ 1,421,000	$ 3,396,000	$ 4,262,000
Interest cost		1,814,000	1,731,000	5,442,000	5,193,000
Expected return on plan assets		(2,411,000)	(2,499,000)	(7,232,000)	(7,496,000)
Amortization of prior service cost (credit)		28,000	104,000	84,000	312,000
Amortization of net loss		1,654,000	1,981,000	4,962,000	5,943,000
Net benefit cost recognized for financial reporting		2,217,000	2,738,000	6,652,000	8,214,000
Total contributions to the pension plans during the period	8,000,000
Postretirement Health Care Benefits
Components of Net Periodic Benefit Cost [Abstract]
Service cost		9,000	6,000	26,000	18,000
Interest cost		198,000	190,000	593,000	570,000
Expected return on plan assets		(13,000)	(11,000)	(39,000)	(32,000)
Amortization of prior service cost (credit)		(88,000)	(88,000)	(263,000)	(264,000)
Amortization of net loss		167,000	241,000	500,000	723,000
Net benefit cost recognized for financial reporting		273,000	338,000	817,000	1,015,000
Xcel Energy Inc. | Pension Benefits
Components of Net Periodic Benefit Cost [Abstract]
Total contributions to the pension plans during the period	$ 130,000,000
Number of Xcel Energy's pension plans to which contributions were made	3