Benefit Plans and Other Postretirement Benefits (Tables)

12 Months Ended

Dec. 31, 2017

Benefit Plans and Other Postretirement Benefits [Abstract]

Projected Benefit Payments for the Pension and Postretirement Benefit Plans

The following table lists Xcel Energy’s projected benefit payments for the pension and postretirement benefit plans:

(Millions of Dollars)	Projected Pension Benefit Payments		Gross Projected Postretirement Health Care Benefit Payments		Expected Medicare Part D Subsidies		Net Projected Postretirement Health Care Benefit Payments
2018	$	307	$	47	$	2	$	45
2019	262		47		2		45
2020	261		47		2		45
2021	261		47		3		44
2022	266		46		3		43
2023-2027	1,274		212		14		198

Contributions to Multiemployer Plans

There were no other significant changes to the nature or magnitude of the participation of NSP-Minnesota and NSP-Wisconsin in multiemployer plans for the years presented:

(Millions of Dollars)	2017		2016		2015
Multiemployer pension contributions:
NSP-Minnesota	$	12	$	14	$	17
NSP-Wisconsin	—		1		1
Total	$	12	$	15	$	18

Pension Plan [Member]

Benefit Plans and Other Postretirement Benefits [Abstract]

Target Asset Allocations and Plan Assets Measured at Fair Value

The following tables present, for each of the fair value hierarchy levels, Xcel Energy’s pension plan assets that are measured at fair value as of Dec. 31, 2017 and 2016:

	Dec. 31, 2017
(Millions of Dollars)	Level 1			Level 2		Level 3		Investments Measured at NAV		Total
Cash equivalents	$	196		$	—	$	—	$	—	$	196
Commingled funds:
U.S. equity funds	513			—		—		—		513
Non U.S. equity funds	92			—		—		199		291
U.S. corporate bond funds	369			—		—		—		369
Emerging market equity funds	—			—		—		314		314
Emerging market debt funds	75			—		—		166		241
Private equity investments	—			—		—		84		84
Real estate	—			—		—		195		195
Other commingled funds	5			—		—		117		122
Debt securities:
Government securities	—			356		—		—		356
U.S. corporate bonds	—			272		—		—		272
Non U.S. corporate bonds	—			45		—		—		45
Equity securities:
U.S. equities	114			—		—		—		114
Other	(29		)	4		—		1		(24		)
Total	$	1,335		$	677	$	—	$	1,076	$	3,088

	Dec. 31, 2016
(Millions of Dollars)	Level 1		Level 2		Level 3		Investments Measured at NAV			Total
Cash equivalents	$	113	$	—	$	—	$	—		$	113
U.S. equity funds	491		—		—		—			491
Non U.S. equity funds	167		—		—		202			369
U.S. corporate bond funds	268		—		—		—			268
Emerging market equity funds	—		—		—		194			194
Emerging market debt funds	79		—		—		85			164
Commodity funds	—		—		—		21			21
Private equity investments	—		—		—		101			101
Real estate	—		—		—		184		—	184
Other commingled funds	—		—		—		210			210
Debt securities:
Government securities	—		364		—		—			364
U.S. corporate bonds	—		238		—		—			238
Non U.S. corporate bonds	—		38		—		—			38
Mortgage-backed securities	—		6		—		—			6
Asset-backed securities	—		3		—		—			3
Equity securities:
U.S. equities	89		—		—		—			89
Other	—		3		—		—			3
Total	$	1,207	$	652	$	—	$	997		$	2,856

The following table presents the target pension asset allocations for Xcel Energy at Dec. 31 for the upcoming year:

	2017		2016
Domestic and international equity securities	36	%	38	%
Long-duration fixed income and interest rate swap securities	27		27
Short-to-intermediate fixed income securities	20		16
Alternative investments	15		17
Cash	2		2
Total	100	%	100	%

Change in Projected Benefit Obligation

A comparison of the actuarially computed pension benefit obligation and plan assets for Xcel Energy is presented in the following table:

(Millions of Dollars)	2017			2016
Accumulated Benefit Obligation at Dec. 31	$	3,612		$	3,489
Change in Projected Benefit Obligation:
Obligation at Jan. 1	$	3,682		$	3,568
Service cost	94			92
Interest cost	147			160
Plan amendments	(13		)	2
Actuarial loss	259			186
Benefit payments (a)	(341		)	(326		)
Obligation at Dec. 31	$	3,828		$	3,682

Change in Fair Value of Plan Assets

(Millions of Dollars)	2017			2016
Change in Fair Value of Plan Assets:
Fair value of plan assets at Jan. 1	$	2,856		$	2,884
Actual return on plan assets	411			172
Employer contributions	162			125
Benefit payments (a)	(341		)	(325		)
Fair value of plan assets at Dec. 31	$	3,088		$	2,856

Funded Status of Plans

(Millions of Dollars)	2017			2016
Funded Status of Plans at Dec. 31:
Funded status (b)	$	(740	)	$	(826	)

^(a)  2017 amount includes approximately $174 million of lump-sum benefit payments used in the determination of a settlement charge.

^(b)  Amounts are recognized in noncurrent liabilities on Xcel Energy’s consolidated balance sheets.

Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost

(Millions of Dollars)	2017			2016
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost:
Net loss	$	1,709		$	1,836
Prior service credit	(25		)	(5		)
Total	$	1,684		$	1,831

Amounts Not Yet Recognized as Components of Net Periodic Benefit Costs Recorded on the Balance Sheet Based Upon Expected Recovery in Rates

(Millions of Dollars)	2017		2016
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates:
Current regulatory assets	$	100	$	101
Noncurrent regulatory assets	1,511		1,650
Deferred income taxes	19		31
Net-of-tax accumulated OCI	54		49
Total	$	1,684	$	1,831

Schedule of Assumptions Used

	2017		2016		2015
Significant Assumptions Used to Measure Costs:
Discount rate	4.13	%	4.66	%	4.11	%
Expected average long-term increase in compensation level	3.75		4.00		3.75
Expected average long-term rate of return on assets	6.87		6.87		7.09

Measurement date Dec. 31, 2017 Dec. 31, 2016

	2017		2016
Significant Assumptions Used to Measure Benefit Obligations:
Discount rate for year-end valuation	3.63	%	4.13	%
Expected average long-term increase in compensation level	3.75		3.75
Mortality table	RP-2014		RP-2014

Components of Net Periodic Benefit Costs

The components of Xcel Energy’s net periodic pension cost were:

(Millions of Dollars)	2017			2016			2015
Service cost	$	94		$	92		$	99
Interest cost	147			160			149
Expected return on plan assets	(209		)	(210		)	(214		)
Amortization of prior service credit	(2		)	(2		)	(2		)
Amortization of net loss	107			97			125
Settlement charge (a)	81			—			—
Net periodic pension cost	218			137			157
Costs not recognized due to effects of regulation	(79		)	(15		)	(29		)
Net benefit cost recognized for financial reporting	$	139		$	122		$	128

^(a)  A settlement charge is required when the amount of all lump-sum distributions during the year is greater than the sum of the service and interest cost components of the annual net periodic pension cost. In the fourth quarter of 2017 as a result of lump-sum distributions during the 2017 plan year, Xcel Energy recorded a total pension settlement charge of $81 million, the majority of which was not recognized due to the effects of regulation. A total of $8 million of that amount was recorded in O&M expenses in the fourth quarter of 2017.

Other Postretirement Benefits Plan [Member]

Benefit Plans and Other Postretirement Benefits [Abstract]

Target Asset Allocations and Plan Assets Measured at Fair Value

The following table presents the target postretirement asset allocations for Xcel Energy at Dec. 31 for the upcoming year:

	2017		2016
Domestic and international equity securities	24	%	25	%
Short-to-intermediate fixed income securities	60		57
Alternative investments	9		13
Cash	7		5
Total	100	%	100	%

The following tables present, for each of the fair value hierarchy levels, Xcel Energy’s postretirement benefit plan assets that are measured at fair value as of Dec. 31, 2017 and 2016:

	Dec. 31, 2017
(Millions of Dollars)	Level 1		Level 2		Level 3		Investments Measured at NAV		Total
Cash equivalents	$	29	$	—	$	—	$	—	$	29
Insurance contracts	—		50		—		—		50
Commingled funds:
U.S. equity funds	74		—		—		—		74
U.S fixed income funds	34		—		—		—		34
Emerging market debt funds	40		—		—		—		40
Debt securities:
Government securities	—		57		—		—		57
U.S. corporate bonds	—		63		—		—		63
Non U.S. corporate bonds	—		21		—		—		21
Asset-backed securities	—		23		—		—		23
Mortgage-backed securities	—		34		—		—		34
Equity securities:
Non U.S. equities	35		—		—		—		35
Other	—		1		—		—		1
Total	$	212	$	249	$	—	$	—	$	461

	Dec. 31, 2016
(Millions of Dollars)	Level 1		Level 2		Level 3		Investments Measured at NAV		Total
Cash equivalents	$	21	$	—	$	—	$	—	$	21
Insurance contracts	—		47		—		—		47
Commingled funds:
U.S. equity funds	54		—		—		—		54
U.S fixed income funds	27		—		—		—		27
Emerging market debt funds	30		—		—		—		30
Other commingled funds	—		—		—		55		55
Debt securities:
Government securities	—		38		—		—		38
U.S. corporate bonds	—		62		—		—		62
Non U.S. corporate bonds	—		17		—		—		17
Asset-backed securities	—		19		—		—		19
Mortgage-backed securities	—		29		—		—		29
Equity securities:
Non U.S. equities	41		—		—		—		41
Other	—		2		—		—		2
Total	$	173	$	214	$	—	$	55	$	442

Change in Projected Benefit Obligation

A comparison of the actuarially computed benefit obligation and plan assets for Xcel Energy is presented in the following table:

(Millions of Dollars)	2017			2016
Change in Projected Benefit Obligation:
Obligation at Jan. 1	$	603		$	584
Service cost	2			2
Interest cost	24			26
Medicare subsidy reimbursements	1			2
Plan participants’ contributions	8			7
Actuarial loss	33			33
Benefit payments	(50		)	(51		)
Obligation at Dec. 31	$	621		$	603

Change in Fair Value of Plan Assets

(Millions of Dollars)	2017			2016
Change in Fair Value of Plan Assets:
Fair value of plan assets at Jan. 1	$	442		$	448
Actual return on plan assets	41			20
Plan participants’ contributions	8			7
Employer contributions	20			18
Benefit payments	(50		)	(51		)
Fair value of plan assets at Dec. 31	$	461		$	442

Funded Status of Plans

(Millions of Dollars)	2017			2016
Funded Status of Plans at Dec. 31:
Funded status	$	(160	)	$	(161	)
Current liabilities	(3		)	(6		)
Noncurrent liabilities	(157		)	(155		)
Net postretirement amounts recognized on consolidated balance sheets	$	(160	)	$	(161	)

Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost

(Millions of Dollars)	2017			2016
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost:
Net loss	$	147		$	136
Prior service credit	(44		)	(54		)
Total	$	103		$	82

Amounts Not Yet Recognized as Components of Net Periodic Benefit Costs Recorded on the Balance Sheet Based Upon Expected Recovery in Rates

(Millions of Dollars)	2017			2016
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates:
Noncurrent regulatory assets	$	107		$	91
Current regulatory liabilities	(1		)	(1		)
Noncurrent regulatory liabilities	(10		)	(14		)
Deferred income taxes	2			2
Net-of-tax accumulated OCI	5			4
Total	$	103		$	82

Schedule of Assumptions Used

Measurement date Dec. 31, 2017 Dec. 31, 2016

	2017		2016
Significant Assumptions Used to Measure Benefit Obligations:
Discount rate for year-end valuation	3.62	%	4.13	%
Mortality table	RP 2014		RP 2014
Health care costs trend rate — initial: Pre-65	7.00	%	5.50	%
Health care costs trend rate — initial: Post-65	5.50	%	5.50	%

	2017		2016		2015
Significant Assumptions Used to Measure Costs:
Discount rate	4.13	%	4.65	%	4.08	%
Expected average long-term rate of return on assets	5.80		5.80		5.80

Effects of One-Percent Change in Assumed Health Care Cost Trend Rate

A one-percent change in the assumed health care cost trend rate would have the following effects on Xcel Energy:

	One-Percentage Point
(Millions of Dollars)	Increase		Decrease
APBO	$	60	$	(51	)
Service and interest components	3		(2		)

Components of Net Periodic Benefit Costs

The components of Xcel Energy’s net periodic postretirement benefit costs were:

(Millions of Dollars)	2017			2016			2015
Service cost	$	2		$	2		$	2
Interest cost	24			26			25
Expected return on plan assets	(25		)	(25		)	(26		)
Amortization of prior service credit	(11		)	(11		)	(11		)
Amortization of net loss	7			4			6
Net periodic postretirement (credit) cost	$	(3	)	$	(4	)	$	(4	)