CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
OPERATING REVENUES (NOTE 2)	$ 929,590	$ 869,501	$ 1,591,520	$ 1,610,031
OPERATING EXPENSES
Fuel and purchased power	238,382	242,222	426,903	472,810
Operations and maintenance	219,392	227,543	440,710	473,177
Depreciation and amortization	152,482	147,374	306,561	296,081
Taxes other than income taxes	56,768	55,090	113,536	110,180
Other expenses	692	683	1,514	1,110
Total	667,716	672,912	1,289,224	1,353,358
OPERATING INCOME	261,874	196,589	302,296	256,673
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	8,811	7,572	16,508	18,760
Pension and other postretirement non-service credits - net	14,142	6,374	28,053	11,488
Other income (Note 9)	16,670	12,885	29,239	20,054
Other expense (Note 9)	(4,036)	(4,350)	(8,820)	(8,708)
Total	35,587	22,481	64,980	41,594
INTEREST EXPENSE
Interest charges	62,690	57,465	121,924	118,118
Allowance for borrowed funds used during construction	(4,749)	(4,494)	(8,825)	(11,159)
Total	57,941	52,971	113,099	106,959
INCOME BEFORE INCOME TAXES	239,520	166,099	254,177	191,308
INCOME TAXES	41,061	17,080	20,852	19,498
NET INCOME	198,459	149,019	233,325	171,810
Less: Net income attributable to noncontrolling interests (Note 6)	4,874	4,874	9,747	9,747
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 193,585	$ 144,145	$ 223,578	$ 162,063
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - BASIC (in shares)	112,638	112,337	112,616	112,381
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - DILUTED (in shares)	112,879	112,651	112,871	112,734
EARNINGS PER WEIGHTED-AVERAGE COMMON SHARE OUTSTANDING
Net income attributable to common shareholders - basic (in dollars per share)	$ 1.72	$ 1.28	$ 1.99	$ 1.44
Net income attributable to common shareholders - diluted (in dollars per share)	$ 1.71	$ 1.28	$ 1.98	$ 1.44
APS
OPERATING REVENUES (NOTE 2)	$ 929,590	$ 869,501	$ 1,591,520	$ 1,610,031
OPERATING EXPENSES
Fuel and purchased power	238,382	242,222	426,903	472,810
Operations and maintenance	216,221	224,143	434,486	464,518
Depreciation and amortization	152,460	147,354	306,518	296,039
Taxes other than income taxes	56,758	55,081	113,516	110,159
Other expenses	692	683	1,514	1,110
Total	664,513	669,483	1,282,937	1,344,636
OPERATING INCOME	265,077	200,018	308,583	265,395
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	8,811	7,572	16,508	18,760
Pension and other postretirement non-service credits - net	14,421	6,757	28,683	12,256
Other income (Note 9)	13,272	11,691	24,905	18,107
Other expense (Note 9)	(3,859)	(3,428)	(8,527)	(7,306)
Total	32,645	22,592	61,569	41,817
INTEREST EXPENSE
Interest charges	56,802	53,591	112,538	110,256
Allowance for borrowed funds used during construction	(4,749)	(4,494)	(8,825)	(11,159)
Total	52,053	49,097	103,713	99,097
INCOME BEFORE INCOME TAXES	245,669	173,513	266,439	208,115
INCOME TAXES	43,677	18,463	24,229	19,916
NET INCOME	201,992	155,050	242,210	188,199
Less: Net income attributable to noncontrolling interests (Note 6)	4,874	4,874	9,747	9,747
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 197,118	$ 150,176	$ 232,463	$ 178,452