Investments in Nuclear Decommissioning Trusts and Other Special Use Funds (Details) - APS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Nuclear decommissioning trust fund assets
Fair Value	$ 1,422,494		$ 1,422,494		$ 1,653,167
Total Unrealized Gains			330,029		475,670
Total Unrealized Losses			(57,009)		(4,063)
Amortized cost	971,000		971,000		972,000
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	6,282	$ 1,406	7,305	$ 4,374
Realized losses	(12,439)	(1,146)	(19,674)	(5,294)
Proceeds from the sale of securities	330,432	207,864	691,670	587,842
Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Fair Value	1,076,088		1,076,088		1,294,757
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	6,282	1,406	7,305	4,374
Realized losses	(12,439)	(1,146)	(19,674)	(5,294)
Proceeds from the sale of securities	309,966	190,340	629,659	425,068
Other Special Use Funds
Nuclear decommissioning trust fund assets
Fair Value	346,406		346,406		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	0	0	0
Proceeds from the sale of securities	20,466	$ 17,524	62,011	$ 162,774
Equity securities
Nuclear decommissioning trust fund assets
Equity securities	502,485		502,485		687,882
Total Unrealized Gains			327,032		451,387
Total Unrealized Losses			(183)		0
Equity securities | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Equity securities	473,392		473,392		640,312
Equity securities | Other Special Use Funds
Nuclear decommissioning trust fund assets
Equity securities	29,093		29,093		47,570
Available for sale-fixed income securities
Nuclear decommissioning trust fund assets
Fair Value	917,670		917,670		992,131
Total Unrealized Gains			2,997		24,283
Total Unrealized Losses			(56,826)		(4,063)
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	100,866		100,866
1 year – 5 years	373,996		373,996
5 years – 10 years	170,310		170,310
Greater than 10 years	272,498		272,498
Total	917,670		917,670
Available for sale-fixed income securities | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Fair Value	601,295		601,295		682,227
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	13,114		13,114
1 year – 5 years	192,566		192,566
5 years – 10 years	127,287		127,287
Greater than 10 years	268,328		268,328
Total	601,295		601,295
Available for sale-fixed income securities | Other Special Use Funds
Nuclear decommissioning trust fund assets
Fair Value	316,375		316,375		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	47,528		47,528
1 year – 5 years	31,422		31,422
5 years – 10 years	0		0
Greater than 10 years	4,170		4,170
Total	83,120		83,120
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	40,224		40,224
1 year – 5 years	150,008		150,008
5 years – 10 years	43,023		43,023
Greater than 10 years	0		0
Total	233,255		233,255
Other
Nuclear decommissioning trust fund assets
Fair Value	2,339		2,339		(26,846)
Total Unrealized Gains			0		0
Total Unrealized Losses			0		0
Other | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Fair Value	1,401		1,401		(27,782)
Other | Other Special Use Funds
Nuclear decommissioning trust fund assets
Fair Value	$ 938		$ 938		$ 936