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 (Credit) [Abstract]
Service cost		$ 5,985,000	$ 6,302,000	$ 17,955,000	$ 18,905,000
Interest cost		13,319,000	11,540,000	39,957,000	34,620,000
Expected return on plan assets		(17,677,000)	(15,955,000)	(53,031,000)	(47,865,000)
Amortization of transition obligation		0	0	0	0
Amortization of prior service credit		(773,000)	(266,000)	(2,319,000)	(798,000)
Amortization of net loss		8,473,000	10,855,000	25,419,000	32,563,000
Net benefit cost (credit) recognized for financial reporting		9,327,000	12,476,000	27,981,000	37,425,000
Total contributions to the pension plans during the period	35,100,000
Postretirement Health Care Benefits
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		479,000	803,000	1,436,000	2,409,000
Interest cost		5,926,000	5,934,000	17,778,000	17,802,000
Expected return on plan assets		(7,554,000)	(7,307,000)	(22,661,000)	(21,921,000)
Amortization of transition obligation		0	196,000	0	588,000
Amortization of prior service credit		(1,562,000)	(1,229,000)	(4,685,000)	(3,687,000)
Amortization of net loss		1,609,000	3,490,000	4,826,000	10,469,000
Net benefit cost (credit) recognized for financial reporting		(1,102,000)	1,887,000	(3,306,000)	5,660,000
Xcel Energy Inc. | Pension Benefits
Components of Net Periodic Benefit Cost (Credit) [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