Fair Value of Financial Assets and Liabilities (Tables)

3 Months Ended

Mar. 31, 2021

Fair Value Disclosures [Abstract]

Gross Notional Amounts of Commodity FTRs

Amounts in Millions (a)	March 31, 2021	Dec. 31, 2020
Megawatt hours of electricity	8	5

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

Derivative Assets and Liabilities Measured at Fair Value on a Recurring Basis by Hierarchy Level

Recurring Fair Value Measurements — SPS’ derivative assets and liabilities measured at fair value on a recurring basis:

	March 31, 2021												Dec. 31, 2020
	Fair Value						Fair Value Total		Netting (a)		Total		Fair Value						Fair Value Total		Netting (a)		Total
(Millions of Dollars)	Level 1		Level 2		Level 3								Level 1		Level 2		Level 3
Current derivative assets
Other derivative instruments:
Electric commodity	$	—	$	—	$	10	$	10	$	—	$	10	$	—	$	—	$	7	$	7	$	—	$	7
Total current derivative assets	$	—	$	—	$	10	$	10	$	—	10		$	—	$	—	$	7	$	7	$	—	7
PPAs (b)											3												3
Current derivative instruments											$	13											$	10
Noncurrent derivative assets
Electric commodity	$	—	$	—	$	2	$	2	$	—	$	2	$	—	$	—	$	—	$	—	$	—	$	—
PPAs (b)											9												9
Noncurrent derivative instruments											$	11											$	9

	March 31, 2021							Dec. 31, 2020
	Fair Value			Fair Value Total	Netting (a)	Total		Fair Value			Fair Value Total	Netting (a)	Total
(Millions of Dollars)	Level 1	Level 2	Level 3					Level 1	Level 2	Level 3
Current derivative liabilities
PPAs (b)						$	4						$	4
Current derivative instruments						$	4						$	4
Noncurrent derivative liabilities
PPAs (b)						$	8						$	9
Noncurrent derivative instruments						$	8						$	9

(a)SPS nets derivative instruments and related collateral on its balance sheets when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at March 31, 2021 and Dec. 31, 2020. At March 31, 2021 and Dec. 31, 2020, derivative assets and liabilities include no obligations to return cash collateral or rights to reclaim cash collateral. The counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

(b)During 2006, SPS 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.

Changes in Level 3 Commodity Derivatives

Changes in Level 3 commodity derivatives for the three months ended March 31, 2021 and 2020:

	Three Months Ended March 31
(Millions of Dollars)	2021		2020
Balance at Jan. 1	$	7	$	12
Purchases	—		12
Settlements	(9)		(5)
Net transactions recorded during the period:
Net gains (losses) recognized as regulatory assets and liabilities	14		(2)
Balance at March 31	$	12	$	17

Carrying Amount and Fair Value of Long-term Debt

Other financial instruments for which the carrying amount did not equal fair value:

	March 31, 2021				Dec. 31, 2020
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt	$	3,011	$	3,286	$	2,764	$	3,381