Benefit Plans and Other Postretirement Benefits, Pension Plan Benefit Obligations, Cash Flows and Benefit Costs (Details) - Pension Plans $ in Thousands		1 Months Ended	12 Months Ended
		Jan. 31, 2017 USD ($) Plan	Dec. 31, 2016 USD ($) Plan	Dec. 31, 2015 USD ($) Plan	Dec. 31, 2014 USD ($) Plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated Benefit Obligation at Dec. 31			$ 3,488,758	$ 3,368,239
Change in Projected Benefit Obligation [Roll Forward]
Obligation at Jan. 1		$ 3,681,618	3,567,927	3,746,752
Service cost			91,739	99,311	$ 88,342
Interest cost			160,102	148,524	156,619
Plan amendments			1,922	0
Actuarial (gain) loss			185,469	(169,678)
Benefit payments			(325,541)	(256,982)
Obligation at Dec. 31			3,681,618	3,567,927	3,746,752
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1		$ 2,855,813	2,883,780	3,083,771
Actual return (loss) on plan assets			172,359	(33,102)
Employer contributions			125,215	90,093
Benefit payments			(325,541)	(256,982)
Fair value of plan assets at Dec. 31			2,855,813	2,883,780	$ 3,083,771
Funded Status of Plans at Dec. 31 [Abstract]
Funded status	[1]		(825,805)	(684,147)
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost [Abstract]
Net loss			1,835,966	1,710,097
Prior service (credit) cost			(5,232)	(9,073)
Total			1,830,734	1,701,024
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates [Abstract]
Current regulatory assets			101,426	105,426
Noncurrent regulatory assets			1,649,482	1,520,975
Deferred income taxes			31,032	29,002
Net-of-tax accumulated other comprehensive income			48,794	45,621
Total			$ 1,830,734	$ 1,701,024
Significant Assumptions Used to Measure Benefit Obligations [Abstract]
Discount rate for year-end valuation (as a percent)			4.13%	4.66%
Expected average long-term increase in compensation level (as a percent)			3.75%	4.00%
Mortality table			RP-2014	RP-2014
Cash Flows [Abstract]
Number of pension plans to which contributions were made | Plan			4	4	4
Total contributions to Xcel Energy's pension plans during the period			$ 125,200	$ 90,100	$ 130,600
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost			91,739	99,311	88,342
Interest cost			160,102	148,524	156,619
Expected return on plan assets			(210,299)	(213,890)	(207,205)
Amortization of prior service cost (credit)			(1,919)	(1,805)	(1,746)
Amortization of net loss			97,539	125,152	116,762
Net periodic benefit cost			137,162	157,292	152,772
Costs not recognized due to regulation			(15,459)	(29,633)	(26,315)
Net benefit cost recognized for financial reporting			$ 121,703	$ 127,659	$ 126,457
Significant Assumptions Used to Measure Costs [Abstract]
Discount rate (as a percent)			4.66%	4.11%	4.75%
Expected average long-term increase in compensation level (as a percent)			4.00%	3.75%	3.75%
Expected average long-term rate of return on assets (as a percent)			6.87%	7.09%	7.05%
Expected average long-term rate of return on assets for next fiscal year (as a percent)			6.87%
Subsequent Event
Cash Flows [Abstract]
Number of pension plans to which contributions were made | Plan		4
Total contributions to Xcel Energy's pension plans during the period		$ 150,000

[1] Amounts are recognized in noncurrent liabilities on Xcel Energy’s consolidated balance sheets.