Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	$ 4,992,135	$ 4,791,319	$ 4,992,135	$ 4,791,319
Total other comprehensive income	1,573	1,610	2,602	4,151
Balance at end of period			4,719,457	4,519,102
AOCI Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(42,146)	(63,990)	(42,146)	(63,990)
Balance at end of period	(43,719)	(65,600)	(44,748)	(68,141)
Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
OCI (loss) before reclassifications	(29)	(151)	(595)	(926)
Amounts reclassified from accumulated other comprehensive loss	798	892	2,564	3,742
Total other comprehensive income	769	741	1,969	2,816
Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
OCI (loss) before reclassifications	0	0	(1,585)	(969)
Amounts reclassified from accumulated other comprehensive loss	804	869	2,218	2,304
Total other comprehensive income	804	869	633	1,335
Arizona Public Service Company
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	5,085,440	4,894,822	5,085,440	4,894,822
Total other comprehensive income	1,568	1,611	2,737	4,293
Balance at end of period			4,814,794	4,629,852
Arizona Public Service Company | AOCI Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(24,360)	(44,040)	(24,360)	(44,040)
Balance at end of period	(25,928)	(45,651)	(27,097)	(48,333)
Arizona Public Service Company | Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
OCI (loss) before reclassifications	(29)	(151)	(595)	(926)
Amounts reclassified from accumulated other comprehensive loss	798	892	2,564	3,742
Total other comprehensive income	769	741	1,969	2,816
Arizona Public Service Company | Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
OCI (loss) before reclassifications	0	0	(1,521)	(927)
Amounts reclassified from accumulated other comprehensive loss	799	870	2,289	2,404
Total other comprehensive income	$ 799	$ 870	$ 768	$ 1,477