Investments in Nuclear Decommissioning Trusts and Other Special Use Funds (Details) - APS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Nuclear decommissioning trust fund assets
Fair Value	$ 1,385,307		$ 1,385,307		$ 1,653,167
Total Unrealized Gains			303,763		475,670
Total Unrealized Losses			(88,101)		(4,063)
Amortized cost	986,000		986,000		972,000
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	788	$ 1,652	8,093	$ 6,026
Realized losses	(6,908)	(1,562)	(26,582)	(6,856)
Proceeds from the sale of securities	218,817	209,336	910,487	797,178
Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Fair Value	1,025,913		1,025,913		1,294,757
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	788	1,652	8,093	6,026
Realized losses	(6,908)	(1,555)	(26,582)	(6,849)
Proceeds from the sale of securities	153,573	181,728	783,232	606,796
Other Special Use Funds
Nuclear decommissioning trust fund assets
Fair Value	359,394		359,394		358,410
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	0	0	0	0
Realized losses	0	(7)	0	(7)
Proceeds from the sale of securities	65,244	$ 27,608	127,255	$ 190,382
Equity securities
Nuclear decommissioning trust fund assets
Equity securities	479,540		479,540		687,882
Total Unrealized Gains			302,627		451,387
Total Unrealized Losses			(458)		0
Equity securities | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Equity securities	440,971		440,971		640,312
Equity securities | Other Special Use Funds
Nuclear decommissioning trust fund assets
Equity securities	38,569		38,569		47,570
Available for sale-fixed income securities
Nuclear decommissioning trust fund assets
Fair Value	899,395		899,395		992,131
Total Unrealized Gains			1,136		24,283
Total Unrealized Losses			(87,618)		(4,063)
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	129,442		129,442
1 year – 5 years	380,698		380,698
5 years – 10 years	120,566		120,566
Greater than 10 years	268,689		268,689
Total	899,395		899,395
Available for sale-fixed income securities | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Fair Value	579,693		579,693		682,227
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	16,334		16,334
1 year – 5 years	184,936		184,936
5 years – 10 years	113,793		113,793
Greater than 10 years	264,630		264,630
Total	579,693		579,693
Available for sale-fixed income securities | Other Special Use Funds
Nuclear decommissioning trust fund assets
Fair Value	319,702		319,702		309,904
Available for sale-fixed income securities | Coal Reclamation Escrow Account
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	53,384		53,384
1 year – 5 years	34,386		34,386
5 years – 10 years	0		0
Greater than 10 years	4,059		4,059
Total	91,829		91,829
Available for sale-fixed income securities | Active Union Employee Medical Account
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	59,724		59,724
1 year – 5 years	161,376		161,376
5 years – 10 years	6,773		6,773
Greater than 10 years	0		0
Total	227,873		227,873
Other
Nuclear decommissioning trust fund assets
Fair Value	6,372		6,372		(26,846)
Total Unrealized Gains			0		0
Total Unrealized Losses			(25)		0
Other | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Fair Value	5,249		5,249		(27,782)
Other | Other Special Use Funds
Nuclear decommissioning trust fund assets
Fair Value	$ 1,123		$ 1,123		$ 936