Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	$ 4,719,183	$ 4,525,643	$ 4,719,183	$ 4,525,643
Total other comprehensive income	51	782	1,029	2,541
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	(43,719)	(65,600)	(43,719)	(65,600)
Balance at end of period	(43,770)	(66,382)	(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	128	25	(566)	(775)
Amounts reclassified from accumulated other comprehensive loss	624	874	1,766	2,850
Total other comprehensive income	752	899	1,200	2,075
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	(1,585)	(969)	(1,585)	(969)
Amounts reclassified from accumulated other comprehensive loss	884	852	1,414	1,435
Total other comprehensive income	(701)	(117)	(171)	466
Arizona Public Service Company
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	4,809,779	4,627,164	4,809,779	4,627,164
Total other comprehensive income	110	825	1,169	2,682
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	(25,928)	(45,651)	(25,928)	(45,651)
Balance at end of period	(26,038)	(46,476)	(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	128	25	(566)	(775)
Amounts reclassified from accumulated other comprehensive loss	624	874	1,766	2,850
Total other comprehensive income	752	899	1,200	2,075
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	(1,521)	(927)	(1,521)	(927)
Amounts reclassified from accumulated other comprehensive loss	879	853	1,490	1,534
Total other comprehensive income	$ (642)	$ (74)	$ (31)	$ 607