Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ (65,600)	$ (74,217)	$ (68,141)	$ (78,053)
Total other comprehensive income	1,610	11,815	4,151	15,651
Ending balance	(63,990)	(62,402)	(63,990)	(62,402)
Derivative Instruments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
OCI (loss) before reclassifications	(151)	(91)	(926)	(472)
Amounts reclassified from accumulated other comprehensive loss	892	5,939	3,742	11,009
Total other comprehensive income	741	5,848
Pension and Other Postretirement Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
OCI (loss) before reclassifications	0	5,231	(969)	3,159
Amounts reclassified from accumulated other comprehensive loss	869	736	2,304	1,955
Total other comprehensive income	869	5,967
Arizona Public Service Company
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(45,651)	(49,400)	(48,333)	(53,372)
Total other comprehensive income	1,611	6,584	4,293	10,556
Ending balance	(44,040)	(42,816)	(44,040)	(42,816)
Arizona Public Service Company | Derivative Instruments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
OCI (loss) before reclassifications	(151)	(91)	(926)	(472)
Amounts reclassified from accumulated other comprehensive loss			3,742	11,010
Total other comprehensive income			2,816	10,538
Arizona Public Service Company | Pension and Other Postretirement Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
OCI (loss) before reclassifications	$ 0	$ 0	(927)	(2,041)
Amounts reclassified from accumulated other comprehensive loss			2,404	2,059
Total other comprehensive income			$ 1,477	$ 18