Retirement Plans and Other Benefits (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Details related to accumulated other comprehensive loss
Accumulated other comprehensive loss	$ 54,995,000	$ 64,416,000
Weighted-average assumptions used to determine benefit obligations
Rate of compensation increase (as a percent)	4.00%	4.00%
Initial healthcare cost trend rate (as a percent)	7.50%	7.50%
Ultimate healthcare cost trend rate (as a percent)	5.00%	5.00%	5.00%
Number of years to ultimate trend rate	4 years	4 years	4 years
Weighted-average assumptions used to determine net periodic benefit costs
Rate of compensation increase (as a percent)	4.00%	4.00%	4.00%
Expected long-term return on plan assets	7.00%	7.75%	7.75%
Initial healthcare cost trend rate (as a percent)	7.50%	7.50%	8.00%
Ultimate healthcare cost trend rate (as a percent)	5.00%	5.00%	5.00%
Number of years to ultimate trend rate	4 years	4 years	4 years
Pension Benefits
Details related to accumulated other comprehensive loss
Net actuarial loss	344,540,000	644,239,000
Prior service cost (credit)	2,072,000	3,169,000
APS's portion recorded as a regulatory asset	(265,107,000)	(550,471,000)
Income tax benefit	(32,204,000)	(38,303,000)
Accumulated other comprehensive loss	49,301,000	58,634,000
Estimated amounts that will be amortized from accumulated other comprehensive loss and regulatory assets into net periodic benefit cost in 2014
Net actuarial loss	8,363,000
Prior service cost (credit)	874,000
Total amounts estimated to be amortized from accumulated other comprehensive loss and regulatory assets in 2014	9,237,000
Weighted-average assumptions used to determine benefit obligations
Discount rate (as a percent)	4.88%	4.01%
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate (as a percent)	4.01%	4.42%	5.31%
Expected long-term return on plan assets for next fiscal year (as a percent)	6.90%
Other Benefits
Details related to accumulated other comprehensive loss
Net actuarial loss	57,816,000	238,862,000
Prior service cost (credit)	(296,000)	(475,000)
APS's portion recorded as a regulatory asset	(49,298,000)	(230,020,000)
Income tax benefit	(2,528,000)	(2,585,000)
Accumulated other comprehensive loss	5,694,000	5,782,000
Estimated amounts that will be amortized from accumulated other comprehensive loss and regulatory assets into net periodic benefit cost in 2014
Prior service cost (credit)	(179,000)
Total amounts estimated to be amortized from accumulated other comprehensive loss and regulatory assets in 2014	(179,000)
Weighted-average assumptions used to determine benefit obligations
Discount rate (as a percent)	5.10%	4.20%
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate (as a percent)	4.20%	4.59%	5.49%
Expected long-term return on plan assets for next fiscal year (as a percent)	7.10%
Effects of one percentage point change in the assumed initial and ultimate health care cost trend rates
Effect of 1% increase on other postretirement benefits expense, after consideration of amounts capitalized or billed to electric plant participants	13,000,000
Effect of 1% decrease on other postretirement benefits expense, after consideration of amounts capitalized or billed to electric plant participants	(10,000,000)
Effect of 1% increase on service and interest cost components of net periodic other postretirement benefit costs	14,000,000
Effect of 1% decrease on service and interest cost components of net periodic other postretirement benefit costs	(11,000,000)
Effect of 1% increase on the accumulated other postretirement benefit obligation	149,000,000
Effect of 1% decrease on the accumulated other postretirement benefit obligation	$ (120,000,000)