CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
OPERATING REVENUES (NOTE 2)	$ 1,254,501	$ 1,190,787	$ 2,846,021	$ 2,800,818
OPERATING EXPENSES
Fuel and purchased power	353,171	344,862	780,074	817,672
Operations and maintenance	236,971	238,582	677,681	711,759
Depreciation and amortization	152,696	149,450	459,257	445,531
Taxes other than income taxes	54,978	53,809	168,514	163,989
Other expenses	1,677	794	3,191	1,904
Total	799,493	787,497	2,088,717	2,140,855
OPERATING INCOME	455,008	403,290	757,304	659,963
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	8,144	5,917	24,652	24,677
Pension and other postretirement non-service credits - net	14,118	5,752	42,171	17,240
Other income (Note 9)	13,881	15,191	42,888	35,245
Other expense (Note 9)	(5,838)	(5,740)	(14,426)	(14,448)
Total	30,305	21,120	95,285	62,714
INTEREST EXPENSE
Interest charges	61,497	57,481	183,421	175,599
Allowance for borrowed funds used during construction	(4,663)	(3,486)	(13,488)	(14,645)
Total	56,834	53,995	169,933	160,954
INCOME BEFORE INCOME TAXES	428,479	370,415	682,656	561,723
INCOME TAXES	77,234	53,266	98,086	72,764
NET INCOME	351,245	317,149	584,570	488,959
Less: Net income attributable to noncontrolling interests (Note 6)	4,873	4,873	14,620	14,620
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 346,372	$ 312,276	$ 569,950	$ 474,339
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - BASIC (in shares)	112,679	112,463	112,639	112,408
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - DILUTED (in shares)	112,987	112,746	112,912	112,739
EARNINGS PER WEIGHTED-AVERAGE COMMON SHARE OUTSTANDING
Net income attributable to common shareholders - basic (in dollars per share)	$ 3.07	$ 2.78	$ 5.06	$ 4.22
Net income attributable to common shareholders - diluted (in dollars per share)	$ 3.07	$ 2.77	$ 5.05	$ 4.21
APS
OPERATING REVENUES (NOTE 2)	$ 1,254,501	$ 1,190,787	$ 2,846,021	$ 2,800,818
OPERATING EXPENSES
Fuel and purchased power	353,171	344,862	780,074	817,672
Operations and maintenance	233,452	235,440	667,938	699,958
Depreciation and amortization	152,676	149,428	459,194	445,467
Taxes other than income taxes	54,966	53,798	168,482	163,957
Other expenses	1,677	794	3,191	1,904
Total	795,942	784,322	2,078,879	2,128,958
OPERATING INCOME	458,559	406,465	767,142	671,860
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	8,144	5,917	24,652	24,677
Pension and other postretirement non-service credits - net	14,334	6,133	43,017	18,389
Other income (Note 9)	13,328	14,534	38,233	32,641
Other expense (Note 9)	(2,799)	(2,826)	(11,326)	(10,132)
Total	33,007	23,758	94,576	65,575
INTEREST EXPENSE
Interest charges	59,132	53,812	171,670	164,068
Allowance for borrowed funds used during construction	(4,663)	(3,486)	(13,488)	(14,645)
Total	54,469	50,326	158,182	149,423
INCOME BEFORE INCOME TAXES	437,097	379,897	703,536	588,012
INCOME TAXES	81,861	56,154	106,090	76,070
NET INCOME	355,236	323,743	597,446	511,942
Less: Net income attributable to noncontrolling interests (Note 6)	4,873	4,873	14,620	14,620
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 350,363	$ 318,870	$ 582,826	$ 497,322