CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
PROPERTY, PLANT AND EQUIPMENT
Plant in service and held for future use	$ 21,844,618	$ 21,688,661
Accumulated depreciation and amortization	(7,597,037)	(7,504,603)
Net	14,247,581	14,184,058
Construction work in progress	1,418,308	1,329,478
Palo Verde sale leaseback, net of accumulated depreciation (Note 6)	93,199	94,166
Intangible assets, net of accumulated amortization	269,802	273,693
Nuclear fuel, net of accumulated amortization	119,296	106,039
Total property, plant and equipment	16,148,186	15,987,434
INVESTMENTS AND OTHER ASSETS
Nuclear decommissioning trusts (Notes 11 and 12)	1,227,465	1,294,757
Other special use funds (Notes 11 and 12)	349,042	358,410
Assets from risk management activities (Note 7)	91,521	46,908
Other assets	105,605	97,884
Total investments and other assets	1,773,633	1,797,959
CURRENT ASSETS
Cash and cash equivalents	13,968	9,969
Customer and other receivables	324,659	391,923
Accrued unbilled revenues	132,765	133,980
Allowance for doubtful accounts (Note 2)	(24,666)	(25,354)
Materials and supplies (at average cost)	358,287	349,135
Fossil fuel (at average cost)	20,772	18,032
Income tax receivable	6,972	7,514
Assets from risk management activities (Note 7)	206,102	63,481
Deferred fuel and purchased power regulatory asset (Note 4)	354,816	388,148
Other regulatory assets (Note 4)	131,444	130,376
Other current assets	69,474	83,896
Total current assets	1,594,593	1,551,100
DEFERRED DEBITS
Regulatory assets (Note 4)	1,184,246	1,192,987
Operating lease right-of-use assets	896,907	890,057
Assets for pension and other postretirement benefits (Note 5)	563,019	545,723
Other	40,370	37,962
Total deferred debits	2,684,542	2,666,729
TOTAL ASSETS	22,200,954	22,003,222
EQUITY
Retained earnings	3,281,601	3,264,719
Accumulated other comprehensive loss	(53,708)	(54,861)
Total shareholders’ equity	5,930,570	5,906,200
Noncontrolling interests (Note 6)	119,566	115,260
Total equity	6,050,136	6,021,460
Long-term debt less current maturities (Note 3)	7,226,624	6,913,735
CURRENT LIABILITIES
Short-term borrowings (Note 3)	262,950	292,000
Accounts payable	343,255	393,083
Accrued taxes	222,492	168,645
Accrued interest	61,648	57,332
Common dividends payable	0	95,988
Customer deposits	41,628	42,293
Liabilities from risk management activities (Note 7)	1,706	4,373
Liabilities for asset retirements	4,069	4,473
Operating lease liabilities	100,949	100,443
Regulatory liabilities (Note 4)	448,778	296,271
Other current liabilities	109,255	151,968
Total current liabilities	1,596,730	1,756,869
DEFERRED CREDITS AND OTHER
Deferred income taxes	2,318,959	2,311,862
Regulatory liabilities (Note 4)	2,438,672	2,499,213
Liabilities for asset retirements	771,720	762,909
Liabilities for pension benefits (Note 5)	149,856	152,865
Customer advances	314,664	257,151
Coal mine reclamation	175,776	174,616
Deferred investment tax credit	186,251	186,570
Unrecognized tax benefits	4,758	4,657
Operating lease liabilities	735,718	728,401
Other	231,090	232,914
Total deferred credits and other	7,327,464	7,311,158
COMMITMENTS AND CONTINGENCIES (NOTE 8)
TOTAL LIABILITIES AND EQUITY	22,200,954	22,003,222
APS
PROPERTY, PLANT AND EQUIPMENT
Plant in service and held for future use	21,841,156	21,685,200
Accumulated depreciation and amortization	(7,593,747)	(7,501,317)
Net	14,247,409	14,183,883
Construction work in progress	1,404,913	1,327,721
Palo Verde sale leaseback, net of accumulated depreciation (Note 6)	93,199	94,166
Intangible assets, net of accumulated amortization	269,647	273,537
Nuclear fuel, net of accumulated amortization	119,296	106,039
Total property, plant and equipment	16,134,464	15,985,346
INVESTMENTS AND OTHER ASSETS
Nuclear decommissioning trusts (Notes 11 and 12)	1,227,465	1,294,757
Other special use funds (Notes 11 and 12)	349,042	358,410
Assets from risk management activities (Note 7)	91,521	46,908
Other assets	43,661	42,440
Total investments and other assets	1,711,689	1,742,515
CURRENT ASSETS
Cash and cash equivalents	12,120	9,374
Customer and other receivables	323,679	390,533
Accrued unbilled revenues	132,765	133,980
Allowance for doubtful accounts (Note 2)	(24,666)	(25,354)
Materials and supplies (at average cost)	358,287	349,135
Fossil fuel (at average cost)	20,772	18,032
Income tax receivable	5,549	10,756
Assets from risk management activities (Note 7)	206,102	63,481
Deferred fuel and purchased power regulatory asset (Note 4)	354,816	388,148
Other regulatory assets (Note 4)	131,444	130,376
Other current assets	51,392	57,729
Total current assets	1,572,260	1,526,190
DEFERRED DEBITS
Regulatory assets (Note 4)	1,184,246	1,192,987
Operating lease right-of-use assets	891,533	888,207
Assets for pension and other postretirement benefits (Note 5)	554,250	537,092
Other	38,095	37,319
Total deferred debits	2,668,124	2,655,605
TOTAL ASSETS	22,086,537	21,909,656
EQUITY
Common stock	178,162	178,162
Additional paid-in capital	3,171,696	3,021,696
Retained earnings	3,494,432	3,470,235
Accumulated other comprehensive loss	(34,060)	(34,880)
Total shareholders’ equity	6,810,230	6,635,213
Noncontrolling interests (Note 6)	119,566	115,260
Total equity	6,929,796	6,750,473
Long-term debt less current maturities (Note 3)	6,267,482	6,266,693
Total capitalization	13,197,278	13,017,166
CURRENT LIABILITIES
Short-term borrowings (Note 3)	250,000	278,700
Accounts payable	329,412	389,365
Accrued taxes	209,730	152,012
Accrued interest	59,293	56,622
Common dividends payable	0	96,000
Customer deposits	41,628	42,293
Liabilities from risk management activities (Note 7)	1,706	4,373
Liabilities for asset retirements	4,069	4,473
Operating lease liabilities	100,629	100,199
Regulatory liabilities (Note 4)	448,778	296,271
Other current liabilities	106,861	145,286
Total current liabilities	1,552,106	1,565,594
DEFERRED CREDITS AND OTHER
Deferred income taxes	2,334,749	2,331,701
Regulatory liabilities (Note 4)	2,438,672	2,499,213
Liabilities for asset retirements	771,720	762,909
Liabilities for pension benefits (Note 5)	135,867	138,328
Customer advances	314,664	257,151
Coal mine reclamation	175,776	174,616
Deferred investment tax credit	186,251	186,570
Unrecognized tax benefits	37,524	37,423
Operating lease liabilities	730,434	726,572
Other	211,496	212,413
Total deferred credits and other	7,337,153	7,326,896
COMMITMENTS AND CONTINGENCIES (NOTE 8)
TOTAL LIABILITIES AND EQUITY	$ 22,086,537	$ 21,909,656