CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
NET INCOME	$ 28,185	$ 9,326
Derivative instruments:
Net unrealized gain (loss), net of tax expense	(770)	(693)
Reclassification of net realized loss, net of tax expense	1,207	1,141
Pension and other postretirement benefits activity, net of tax expense	522	530
Total other comprehensive income	959	978
COMPREHENSIVE INCOME	29,144	10,304
Less: Comprehensive income attributable to noncontrolling interests	4,873	4,873
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	24,271	5,431
APS
NET INCOME	28,035	12,126
Derivative instruments:
Net unrealized gain (loss), net of tax expense	(770)	(693)
Reclassification of net realized loss, net of tax expense	1,207	1,141
Pension and other postretirement benefits activity, net of tax expense	611	611
Total other comprehensive income	1,048	1,059
COMPREHENSIVE INCOME	29,083	13,185
Less: Comprehensive income attributable to noncontrolling interests	4,873	4,873
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 24,210	$ 8,312