Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	$ 4,740,413	$ 4,553,007
Total other comprehensive income	978	1,759
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	(43,770)	(66,382)
Balance at end of period	(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	(693)	(800)
Amounts reclassified from accumulated other comprehensive loss	1,141	1,976
Total other comprehensive income	448	1,176
Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from accumulated other comprehensive loss	530	583
Total other comprehensive income	530	583
Arizona Public Service Company
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	4,827,980	4,656,183
Total other comprehensive income	1,059	1,857
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	(26,038)	(46,476)
Balance at end of period	(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	(693)	(800)
Amounts reclassified from accumulated other comprehensive loss	1,141	1,976
Total other comprehensive income	448	1,176
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]
Amounts reclassified from accumulated other comprehensive loss	611	681
Total other comprehensive income	$ 611	$ 681