Investments in Nuclear Decommissioning Trusts and Other Special Use Funds (Tables)

3 Months Ended

Mar. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Schedule of Fair Value of APS's Nuclear Decommissioning Trust Fund Assets

The following tables present the unrealized gains and losses based on the original cost of the investment and summarizes the fair value of APS’s nuclear decommissioning trusts and other special use fund assets (dollars in thousands):  

	March 31, 2023
	Fair Value							Total Unrealized Gains		Total Unrealized Losses
Investment Type:	Nuclear Decommissioning Trusts		Other Special Use Funds		Total
Equity securities	$	517,371	$	27,642	$	545,013		$	367,791	$	(39)
Available for sale-fixed income securities	609,381		324,194		933,575		(a)	6,728		(54,178)
Other	(1,135)		1,041		(94)		(b)	1		(11)
Total	$	1,125,617	$	352,877	$	1,478,494		$	374,520	$	(54,228)

(a)As of March 31, 2023, the amortized cost basis of these available-for-sale investments is $981 million.

(b)Represents net pending securities sales and purchases.

	December 31, 2022
	Fair Value							Total Unrealized Gains		Total Unrealized Losses
Investment Type:	Nuclear Decommissioning Trusts		Other Special Use Funds		Total
Equity securities	$	487,240	$	66,974	$	554,214		$	334,817	$	(267)
Available for sale-fixed income securities	582,343		279,294		861,637		(a)	3,177		(68,795)
Other	3,827		963		4,790		(b)	—		(29)
Total	$	1,073,410	$	347,231	$	1,420,641		$	337,994	$	(69,091)

(a)As of December 31, 2022, the amortized cost basis of these available-for-sale investments is $927 million.

(b)Represents net pending securities sales and purchases.

Schedule of Realized Gains and Losses and Proceeds from the Sale of Securities by the Nuclear Decommissioning Trust Funds

:

	Three Months Ended March 31,
	Nuclear Decommissioning Trusts		Other Special Use Funds		Total
2023
Realized gains	$	1,210	$	—	$	1,210
Realized losses	(5,694)		—		(5,694)
Proceeds from the sale of securities (a)	136,185		90,441		226,626
2022
Realized gains	$	1,023	$	—	$	1,023
Realized losses	(7,235)		—		(7,235)
Proceeds from the sale of securities (a)	319,693		41,545		361,238

(a)    Proceeds are reinvested in the nuclear decommissioning trusts and other special use funds, excluding amounts reimbursed to the Company for active union employee medical claims from the active union employee medical account.

Schedule of Fair Value of Fixed Income Securities, Summarized by Contractual Maturities

The fair value of APS’s fixed income securities, summarized by contractual maturities, at March 31, 2023, is as follows (dollars in thousands):

	Nuclear Decommissioning Trusts		Coal Reclamation Escrow Account		Active Union Employee Medical Account		Total
Less than one year	$	14,591	$	53,718	$	74,788	$	143,097
1 year – 5 years	174,911		36,821		110,034		321,766
5 years – 10 years	137,708		—		44,835		182,543
Greater than 10 years	282,171		3,998		—		286,169
Total	$	609,381	$	94,537	$	229,657	$	933,575