CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
OPERATING REVENUES (NOTE 2)	$ 1,000,249	$ 929,590	$ 1,696,724	$ 1,591,520
OPERATING EXPENSES
Fuel and purchased power	269,835	238,382	468,062	426,903
Operations and maintenance	229,690	219,392	459,745	440,710
Depreciation and amortization	158,750	152,482	316,570	306,561
Taxes other than income taxes	59,495	56,768	118,978	113,536
Other expenses	4,093	692	7,449	1,514
Total	721,863	667,716	1,370,804	1,289,224
OPERATING INCOME	278,386	261,874	325,920	302,296
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	9,990	8,811	19,197	16,508
Pension and other postretirement non-service credits — net	28,175	14,142	55,966	28,053
Other income (Note 9)	12,207	16,670	24,636	29,239
Other expense (Note 9)	(5,184)	(4,036)	(9,037)	(8,820)
Total	45,188	35,587	90,762	64,980
INTEREST EXPENSE
Interest charges	62,777	62,690	124,715	121,924
Allowance for borrowed funds used during construction	(5,199)	(4,749)	(10,193)	(8,825)
Total	57,578	57,941	114,522	113,099
INCOME BEFORE INCOME TAXES	265,996	239,520	302,160	254,177
INCOME TAXES	46,560	41,061	42,210	20,852
NET INCOME	219,436	198,459	259,950	233,325
Less: Net income attributable to noncontrolling interests (Note 6)	3,739	4,874	8,612	9,747
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 215,697	$ 193,585	$ 251,338	$ 223,578
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - BASIC (in shares)	112,882	112,638	112,855	112,616
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - DILUTED (in shares)	113,223	112,879	113,158	112,871
EARNINGS PER WEIGHTED-AVERAGE COMMON SHARE OUTSTANDING
Net income attributable to common shareholders - basic (in dollars per share)	$ 1.91	$ 1.72	$ 2.23	$ 1.99
Net income attributable to common shareholders - diluted (in dollars per share)	$ 1.91	$ 1.71	$ 2.22	$ 1.98
APS
OPERATING REVENUES (NOTE 2)	$ 1,000,249	$ 929,590	$ 1,696,724	$ 1,591,520
OPERATING EXPENSES
Fuel and purchased power	269,835	238,382	468,062	426,903
Operations and maintenance	226,698	216,221	453,099	434,486
Depreciation and amortization	158,728	152,460	316,528	306,518
Taxes other than income taxes	59,478	56,758	118,950	113,516
Other expenses	4,093	692	7,449	1,514
Total	718,832	664,513	1,364,088	1,282,937
OPERATING INCOME	281,417	265,077	332,636	308,583
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	9,990	8,811	19,197	16,508
Pension and other postretirement non-service credits — net	28,234	14,421	56,071	28,683
Other income (Note 9)	11,563	13,272	23,523	24,905
Other expense (Note 9)	(4,261)	(3,859)	(7,611)	(8,527)
Total	45,526	32,645	91,180	61,569
INTEREST EXPENSE
Interest charges	59,930	56,802	119,318	112,538
Allowance for borrowed funds used during construction	(5,199)	(4,749)	(10,193)	(8,825)
Total	54,731	52,053	109,125	103,713
INCOME BEFORE INCOME TAXES	272,212	245,669	314,691	266,439
INCOME TAXES	48,725	43,677	51,044	24,229
NET INCOME	223,487	201,992	263,647	242,210
Less: Net income attributable to noncontrolling interests (Note 6)	3,739	4,874	8,612	9,747
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 219,748	$ 197,118	$ 255,035	$ 232,463