CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
OPERATING REVENUES (NOTE 2)	$ 1,308,254	$ 1,254,501	$ 3,004,978	$ 2,846,021
OPERATING EXPENSES
Fuel and purchased power	427,452	353,171	895,514	780,074
Operations and maintenance	232,386	236,971	692,131	677,681
Depreciation and amortization	163,523	152,696	480,093	459,257
Taxes other than income taxes	57,608	54,978	176,586	168,514
Other expenses - net	(2,088)	1,677	5,361	3,191
Total	878,881	799,493	2,249,685	2,088,717
OPERATING INCOME	429,373	455,008	755,293	757,304
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	11,352	8,144	30,549	24,652
Pension and other postretirement non-service credits - net	28,135	14,118	84,101	42,171
Other income (Note 9)	12,083	13,881	36,719	42,888
Other expense (Note 9)	(6,182)	(5,838)	(15,219)	(14,426)
Total	45,388	30,305	136,150	95,285
INTEREST EXPENSE
Interest charges	64,067	61,497	188,782	183,421
Allowance for borrowed funds used during construction	(5,273)	(4,663)	(15,466)	(13,488)
Total	58,794	56,834	173,316	169,933
INCOME BEFORE INCOME TAXES	415,967	428,479	718,127	682,656
INCOME TAXES	71,863	77,234	114,073	98,086
NET INCOME	344,104	351,245	604,054	584,570
Less: Net income attributable to noncontrolling interests (Note 6)	4,306	4,873	12,918	14,620
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 339,798	$ 346,372	$ 591,136	$ 569,950
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - BASIC (in shares)	112,923	112,679	112,878	112,639
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - DILUTED (in shares)	113,217	112,987	113,178	112,912
EARNINGS PER WEIGHTED-AVERAGE COMMON SHARE OUTSTANDING
Net income attributable to common shareholders - basic (in dollars per share)	$ 3.01	$ 3.07	$ 5.24	$ 5.06
Net income attributable to common shareholders - diluted (in dollars per share)	$ 3.00	$ 3.07	$ 5.22	$ 5.05
APS
OPERATING REVENUES (NOTE 2)	$ 1,308,254	$ 1,254,501	$ 3,004,978	$ 2,846,021
OPERATING EXPENSES
Fuel and purchased power	427,452	353,171	895,514	780,074
Operations and maintenance	229,432	233,452	682,531	667,938
Depreciation and amortization	163,484	152,676	480,012	459,194
Taxes other than income taxes	57,591	54,966	176,541	168,482
Other expenses - net	(2,088)	1,677	5,361	3,191
Total	875,871	795,942	2,239,959	2,078,879
OPERATING INCOME	432,383	458,559	765,019	767,142
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	11,352	8,144	30,549	24,652
Pension and other postretirement non-service credits - net	28,191	14,334	84,262	43,017
Other income (Note 9)	11,597	13,328	35,120	38,233
Other expense (Note 9)	(2,196)	(2,799)	(9,807)	(11,326)
Total	48,944	33,007	140,124	94,576
INTEREST EXPENSE
Interest charges	61,362	59,132	180,680	171,670
Allowance for borrowed funds used during construction	(5,273)	(4,663)	(15,466)	(13,488)
Total	56,089	54,469	165,214	158,182
INCOME BEFORE INCOME TAXES	425,238	437,097	739,929	703,536
INCOME TAXES	77,269	81,861	128,313	106,090
NET INCOME	347,969	355,236	611,616	597,446
Less: Net income attributable to noncontrolling interests (Note 6)	4,306	4,873	12,918	14,620
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 343,663	$ 350,363	$ 598,698	$ 582,826