CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
NET INCOME	$ 317,149	$ 319,885	$ 488,959	$ 499,591
Derivative instruments:
Net unrealized loss, net of tax expense	0	0	0	(96)
Reclassification of net realized loss, net of tax benefit	218	451	950	1,316
Pension and other postretirement benefits activity, net of tax expense (benefit)	880	1,099	220	(2,740)
Total other comprehensive income (loss)	1,098	1,550	1,170	(1,520)
COMPREHENSIVE INCOME	318,247	321,435	490,129	498,071
Less: Comprehensive income attributable to noncontrolling interests	4,873	4,873	14,620	14,620
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	313,374	316,562	475,509	483,451
APS
NET INCOME	323,743	343,239	511,942	540,409
Derivative instruments:
Net unrealized loss, net of tax expense	0	0	0	(96)
Reclassification of net realized loss, net of tax benefit	218	451	950	1,316
Pension and other postretirement benefits activity, net of tax expense (benefit)	755	952	(146)	(2,955)
Total other comprehensive income (loss)	973	1,403	804	(1,735)
COMPREHENSIVE INCOME	324,716	344,642	512,746	538,674
Less: Comprehensive income attributable to noncontrolling interests	4,873	4,873	14,620	14,620
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 319,843	$ 339,769	$ 498,126	$ 524,054