Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 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	959	978
Balance at end of period	4,965,940	4,740,413
AOCI Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(43,822)	(44,748)
Balance at end of period	(42,863)	(43,770)
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	(770)	(693)
Amounts reclassified from accumulated other comprehensive loss	1,207	1,141
Total other comprehensive income	437	448
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	522	530
Total other comprehensive income	522	530
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	1,048	1,059
Balance at end of period	5,067,052	4,827,980
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	(25,423)	(27,097)
Balance at end of period	(24,375)	(26,038)
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	(770)	(693)
Amounts reclassified from accumulated other comprehensive loss	1,207	1,141
Total other comprehensive income	437	448
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	611
Total other comprehensive income	$ 611	$ 611