Fair Value of Financial Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Cost and Fair Value of Nuclear Decommissioning Fund Investments

Non-derivative instruments with recurring fair value measurements in the nuclear decommissioning fund:

	Dec. 31, 2018
			Fair Value
(Millions of Dollars)	Cost		Level 1		Level 2		Level 3		NAV		Total
Nuclear decommissioning fund (a)
Cash equivalents	$	24	$	24	$	—	$	—	$	—	$	24
Commingled funds	758		79		—		—		819		898
Debt securities	466		—		436		—		—		436
Equity securities	401		697		—		—		—		697
Total	$	1,649	$	800	$	436	$	—	$	819	$	2,055

^(a)  Reported in nuclear decommissioning fund and other investments on the consolidated balance sheet, which also includes $141 million of equity investments in unconsolidated subsidiaries and $121 million of rabbi trust assets and miscellaneous investments.

	Dec. 31, 2017
			Fair Value
(Millions of Dollars)	Cost		Level 1		Level 2		Level 3		NAV		Total
Nuclear decommissioning fund (a)
Cash equivalents	$	29	$	29	$	—	$	—	$	—	$	29
Commingled funds	701		223		—		—		659		882
Debt securities	438		—		441		—		—		441
Equity securities	423		791		—		—		—		791
Total	$	1,591	$	1,043	$	441	$	—	$	659	$	2,143

^(a)  Reported in nuclear decommissioning fund and other investments on the consolidated balance sheet, which also includes $140 million of equity investments in unconsolidated subsidiaries and $114 million of rabbi trust assets and miscellaneous investments.

For th

Final Contractual Maturity Dates of Debt Securities in the Nuclear Decommissioning Fund by Asset Class

Contractual maturity dates of debt securities in the nuclear decommissioning fund as of Dec. 31, 2018:

	Final Contractual Maturity
(Millions of Dollars)	Due in 1 Year or Less		Due in 1 to 5 Years		Due in 5 to 10 Years		Due after 10 Years		Total
Debt securities	$	10	$	107	$	211	$	108	$	436

Rabbi

Rabbi Trust Securities Amortized Cost and Fair Value Measured on Recurrring Basis [Table Text Block]

rusts

Xcel Energy has established rabbi trusts to provide partial funding for future distributions of its SERP and deferred compensation plan.

Cost and fair value of assets held in rabbi trusts:

	Dec. 31, 2018
			Fair Value
(Millions of Dollars)	Cost		Level 1		Level 2		Level 3		Total
Rabbi Trusts (a)
Cash equivalents	$	16	$	16	$	—	$	—	$	16
Mutual funds	52		51		—		—		51
Total	$	68	$	67	$	—	$	—	$	67

	Dec. 31, 2017
			Fair Value
(Millions of Dollars)	Cost		Level 1		Level 2		Level 3		Total
Rabbi Trusts (a)
Cash equivalents	$	12	$	12	$	—	$	—	$	12
Mutual funds	47		50		—		—		50
Total	$	59	$	62	$	—	$	—	$	62

^(a)  Reported in nuclear decommissioning fund and other investments on the consolidated balance sheet.

Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]

Gross notional amounts of commodity forwards, options and FTRs as of Dec. 31:

(Amounts in Millions) (a) (b)	2018	2017
MWh of electricity	87	68
MMBtu of natural gas	92	37

^(a)  Amounts are not reflective of net positions in the underlying commodities.

^(b)  Notional amounts for options are included on a gross basis, but are weighted for the probability of exercise.

Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) [Table Text Block]

Financial impact of qualifying interest rate and vehicle fuel cash flow hedges on Xcel Energy’s accumulated other comprehensive loss, included in the consolidated statements of common stockholders’ equity and in the consolidated statements of comprehensive income:

(Millions of Dollars)	2018			2017			2016
Accumulated other comprehensive loss related to cash flow hedges at Jan. 1	$	(58	)	$	(51	)	$	(55	)
After-tax net unrealized losses related to derivatives accounted for as hedges	(5		)	—			—
After-tax net realized losses on derivative transactions reclassified into earnings	3			3			4
Adoption of ASU. 2018-02 (a)	—			(10		)	—
Accumulated other comprehensive loss related to cash flow hedges at Dec. 31	$	(60	)	$	(58	)	$	(51	)

^(a)  In 2017, Xcel Energy implemented ASU No. 2018-02 related to TCJA, which resulted in reclassification of certain credit balances within net accumulated other comprehensive loss to retained earnings.

Derivative Instruments, Gain (Loss) [Table Text Block]

Impact of derivative activity:

	Pre-Tax Fair Value Gains (Losses) Recognized During the Period in:
(Millions of Dollars)	Accumulated Other Comprehensive Loss			Regulatory (Assets) and Liabilities
Year Ended Dec. 31, 2018
Derivatives designated as cash flow hedges
Interest rate	$	(7	)	$	—
Total	$	(7	)	$	—
Other derivative instruments
Electric commodity	$	—		$	1
Natural gas commodity	—			10
Total	$	—		$	11
Year Ended Dec. 31, 2017
Other derivative instruments
Electric commodity	$	—		$	10
Natural gas commodity	—			(13		)
Total	$	—		$	(3	)
Year Ended Dec. 31, 2016
Other derivative instruments
Electric commodity	$	—		$	17
Natural gas commodity	—			1
Total	$	—		$	18

	Pre-Tax (Gains) Losses Reclassified into Income During the Period from:							Pre-Tax Gains (Losses) Recognized During the Period in Income
(Millions of Dollars)	Accumulated Other Comprehensive Loss			Regulatory Assets and (Liabilities)
Year Ended Dec. 31, 2018
Derivatives designated as cash flow hedges
Interest rate	$	4	(a)	$	—			$	—
Total	$	4		$	—			$	—
Other derivative instruments
Commodity trading	$	—		$	—			$	14		(b)
Electric commodity	—			(1		)	(c)	—
Natural gas commodity	—			(6		)	(d)	(4		)	(d)
Total	$	—		$	(7	)		$	10
Year Ended Dec. 31, 2017
Derivatives designated as cash flow hedges
Interest rate	$	5	(a)	$	—			$	—
Total	$	5		$	—			$	—
Other derivative instruments
Commodity trading	$	—		$	—			$	10		(b)
Electric commodity	—			(15		)	(c)	—
Natural gas commodity	—			3			(d)	(6		)	(d)
Total	$	—		$	(12	)		$	4
Year Ended Dec. 31, 2016
Derivatives designated as cash flow hedges
Interest rate	$	6	(a)	$	—			$	—
Total	$	6		$	—			$	—
Other derivative instruments
Commodity trading	$	—		$	—			$	2		(b)
Electric commodity	—			(8		)	(c)	—
Natural gas commodity	—			15			(d)	(8		)	(d)
Total	$	—		$	7			$	(6	)

^(a)  Amounts recorded to interest charges.

^(b)  Amounts recorded to electric operating revenues. Portions of these gains and losses are subject to sharing with electric customers through margin-sharing mechanisms and deducted from gross revenue, as appropriate.

^(c)  Amounts recorded to electric fuel and purchased power. These derivative settlement gains and losses are shared with electric customers through fuel and purchased energy cost-recovery mechanisms, and reclassified out of income as regulatory assets or liabilities, as appropriate.

^(d)  Amounts for the year ended Dec. 31, 2018 included $1 million of settlement losses on derivatives entered to mitigate natural gas price risk for electric generation recorded to electric fuel and purchased power, subject to cost-recovery mechanisms and reclassified to a regulatory asset, as appropriate. Such gains and losses for the years ended Dec. 31, 2017 and 2016 were immaterial. Remaining settlement losses for the years ended Dec. 31, 2018, 2017 and 2016 related to natural gas operations and were recorded to cost of natural gas sold and transported. These losses are subject to cost-recovery mechanisms and reclassified out of income to a regulatory asset, as appropriate.

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

Xcel Energy’s derivative assets and liabilities measured at fair value on a recurring basis:

	Dec. 31, 2018													Dec. 31, 2017
	Fair Value						Fair Value Total		Netting (a)					Fair Value						Fair Value Total		Netting (a)
(Millions of Dollars)	Level 1		Level 2		Level 3							Total		Level 1		Level 2		Level 3							Total
Current derivative assets
Commodity trading	$	4	$	92	$	2	$	98	$	(44	)	$	54	$	2	$	22	$	—	$	24	$	(15	)	$	9
Electric commodity	—		—		25		25		—			25		—		—		32		32		(2		)	30
Natural gas commodity	—		4		—		4		—			4		—		—		—		—		—			—
Total current derivative assets	$	4	$	96	$	27	$	127	$	(44	)	83		$	2	$	22	$	32	$	56	$	(17	)	39
PPAs (b)												4													5
Current derivative instruments												$	87												$	44
Noncurrent derivative assets
Other derivative instruments:
Commodity trading	$	—	$	27	$	5	$	32	$	(14	)	$	18	$	—	$	31	$	5	$	36	$	(7	)	$	29
Total noncurrent derivative assets	$	—	$	27	$	5	$	32	$	(14	)	18		$	—	$	31	$	5	$	36	$	(7	)	29
PPAs (b)												16													19
Noncurrent derivative instruments												$	34												$	48

	Dec. 31, 2018													Dec. 31, 2017
	Fair Value						Fair Value Total		Netting (a)					Fair Value						Fair Value Total		Netting (a)
(Millions of Dollars)	Level 1		Level 2		Level 3							Total		Level 1		Level 2		Level 3							Total
Current derivative liabilities
Derivatives designated as cash flow hedges:
Interest rate	$	—	$	7	$	—	$	7	$	—		$	7	$	—	$	—	$	—	$	—	$	—		$	—
Other derivative instruments:
Commodity trading	4		88		2		94		(60		)	34		2		18		—		20		(15		)	5
Electric commodity	—		—		—		—		—			—		—		—		2		2		(2		)	—
Natural gas commodity	—		—		—		—		—			—		—		1		—		1		—			1
Total current derivative liabilities	$	4	$	95	$	2	$	101	$	(60	)	41		$	2	$	19	$	2	$	23	$	(17	)	6
PPAs (b)												20													23
Current derivative instruments												$	61												$	29
Noncurrent derivative liabilities
Other derivative instruments:
Commodity trading	$	—	$	18	$	1	$	19	$	17		$	36	$	—	$	24	$	—	$	24	$	(10	)	$	14
Total noncurrent derivative liabilities	$	—	$	18	$	1	$	19	$	17		36		$	—	$	24	$	—	$	24	$	(10	)	14
PPAs (b)												93													112
Noncurrent derivative instruments												$	129												$	126

^(a)  Xcel Energy nets derivative instruments and related collateral in its consolidated balance sheet when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements as of Dec. 31, 2018 and 2017. At Dec. 31, 2018 and 2017, derivative assets and liabilities include $32 million and $0 million of obligations to return cash collateral, respectively. At Dec. 31, 2018 and 2017, derivative assets and liabilities include rights to reclaim cash collateral of $15 million and $3 million, respectively. Counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

^(b)  During 2006, Xcel Energy qualified these contracts under the normal purchase exception. Based on this qualification, the contracts are no longer adjusted to fair value and the previous carrying value of these contracts will be amortized over the remaining contract lives along with the offsetting regulatory assets and liabilities.

Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Table Text Block]

Changes in Level 3 commodity derivatives:

	Year Ended Dec. 31
(Millions of Dollars)	2018			2017			2016
Balance at Jan. 1	$	35		$	17		$	18
Purchases	59			82			35
Settlements	(59		)	(97		)	(89		)
Net transactions recorded during the period:
(Losses) gains recognized in earnings (a)	(1		)	5			—
Net (losses) gains recognized as regulatory assets and liabilities	(5		)	28			53
Balance at Dec. 31	$	29		$	35		$	17

^(a)  Amounts relate to commodity derivatives held at the end of the period.

Fair Value, by Balance Sheet Grouping [Table Text Block]

As of Dec. 31, other financial instruments for which the carrying amount did not equal fair value:

	2018				2017
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	16,209	$	16,755	$	14,977	$	16,531