Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			$ 4,935,912	$ 4,719,457
Total other comprehensive income (loss)	$ (763)	$ 51	196	1,029
Balance at end of period	4,990,077	4,719,183	4,990,077	4,719,183
AOCI Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(42,863)	(43,770)	(43,822)	(44,748)
Balance at end of period	(43,626)	(43,719)	(43,626)	(43,719)
Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
OCI (loss) before reclassifications	7	128	(763)	(566)
Amounts reclassified from accumulated other comprehensive loss	564	624	1,771	1,766
Total other comprehensive income (loss)	571	752	1,008	1,200
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	(2,157)	(1,585)	(2,157)	(1,585)
Amounts reclassified from accumulated other comprehensive loss	823	884	1,345	1,414
Total other comprehensive income (loss)	(1,334)	(701)	(812)	(171)
Arizona Public Service Company
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			5,037,970	4,814,794
Total other comprehensive income (loss)	(737)	110	311	1,169
Balance at end of period	5,082,726	4,809,779	5,082,726	4,809,779
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	(24,375)	(26,038)	(25,423)	(27,097)
Balance at end of period	(25,112)	(25,928)	(25,112)	(25,928)
Arizona Public Service Company | Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
OCI (loss) before reclassifications	7	128	(763)	(566)
Amounts reclassified from accumulated other comprehensive loss	564	624	1,771	1,766
Total other comprehensive income (loss)	571	752	1,008	1,200
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	(2,121)	(1,521)	(2,121)	(1,521)
Amounts reclassified from accumulated other comprehensive loss	813	879	1,424	1,490
Total other comprehensive income (loss)	$ (1,308)	$ (642)	$ (697)	$ (31)