CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
NET INCOME	$ 149,019	$ 171,612	$ 171,810	$ 179,706
Derivative instruments:
Net unrealized gain (loss), net of tax expense	0	0	0	(96)
Reclassification of net realized loss, net of tax expense	404	456	732	865
Pension and other postretirement benefits activity, net of tax benefit	(1,539)	(4,739)	(660)	(3,839)
Total other comprehensive income (loss)	(1,135)	(4,283)	72	(3,070)
COMPREHENSIVE INCOME	147,884	167,329	171,882	176,636
Less: Comprehensive income attributable to noncontrolling interests	4,874	4,874	9,747	9,747
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	143,010	162,455	162,135	166,889
APS
NET INCOME	155,050	182,699	188,199	197,170
Derivative instruments:
Net unrealized gain (loss), net of tax expense	0	0	0	(96)
Reclassification of net realized loss, net of tax expense	404	456	732	865
Pension and other postretirement benefits activity, net of tax benefit	(1,653)	(4,764)	(901)	(3,907)
Total other comprehensive income (loss)	(1,249)	(4,308)	(169)	(3,138)
COMPREHENSIVE INCOME	153,801	178,391	188,030	194,032
Less: Comprehensive income attributable to noncontrolling interests	4,874	4,874	9,747	9,747
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 148,927	$ 173,517	$ 178,283	$ 184,285