Regulatory Matters- Schedule of Regulatory Assets (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Detail of regulatory assets
Regulatory assets, current	$ 148,000,000	$ 138,000,000
Regulatory assets, non-current	1,067,830,000	1,054,087,000
Pension benefits
Detail of regulatory assets
Regulatory assets, current	0	0
Regulatory assets, non-current	479,000,000	485,000,000
Income taxes — allowance for funds used during construction (“AFUDC”) equity
Detail of regulatory assets
Regulatory assets, current	5,000,000	5,000,000
Regulatory assets, non-current	117,000,000	118,000,000
Deferred fuel and purchased power — mark-to-market (Note 7)
Detail of regulatory assets
Regulatory assets, current	66,000,000	51,000,000
Regulatory assets, non-current	72,000,000	46,000,000
Transmission vegetation management
Detail of regulatory assets
Regulatory assets, current	9,000,000	9,000,000
Regulatory assets, non-current	2,000,000	5,000,000
Coal reclamation
Detail of regulatory assets
Regulatory assets, current	0	0
Regulatory assets, non-current	6,000,000	7,000,000
Palo Verde VIEs (Note 6)
Detail of regulatory assets
Regulatory assets, current	0	0
Regulatory assets, non-current	30,000,000	35,000,000
Deferred compensation
Detail of regulatory assets
Regulatory assets, current	0	0
Regulatory assets, non-current	36,000,000	34,000,000
Deferred fuel and purchased power
Detail of regulatory assets
Regulatory assets, current	0	7,000,000
Regulatory assets, non-current	0	0
Tax expense of Medicare subsidy
Detail of regulatory assets
Regulatory assets, current	2,000,000	2,000,000
Regulatory assets, non-current	14,000,000	14,000,000
Loss on reacquired debt
Detail of regulatory assets
Regulatory assets, current	1,000,000	1,000,000
Regulatory assets, non-current	16,000,000	16,000,000
Income taxes — investment tax credit basis adjustment
Detail of regulatory assets
Regulatory assets, current	2,000,000	2,000,000
Regulatory assets, non-current	46,000,000	46,000,000
Pension and other postretirement benefits deferral
Detail of regulatory assets
Regulatory assets, current	2,000,000	4,000,000
Regulatory assets, non-current	0	0
Four Corners cost deferral
Detail of regulatory assets
Regulatory assets, current	7,000,000	7,000,000
Regulatory assets, non-current	68,000,000	70,000,000
Lost fixed cost recovery
Detail of regulatory assets
Regulatory assets, current	43,000,000	38,000,000
Regulatory assets, non-current	0	0
Retired power plant costs
Detail of regulatory assets
Regulatory assets, current	10,000,000	10,000,000
Regulatory assets, non-current	134,000,000	136,000,000
Deferred property taxes
Detail of regulatory assets
Regulatory assets, current	0	0
Regulatory assets, non-current	36,000,000	30,000,000
Other
Detail of regulatory assets
Regulatory assets, current	1,000,000	2,000,000
Regulatory assets, non-current	12,000,000	12,000,000
Arizona Public Service Company
Detail of regulatory assets
Regulatory assets, non-current	$ 1,067,830,000	$ 1,054,087,000