Commitments and Contingencies - Superfund-Related Matters and Southwest Power Outage (Details) $ in Millions					12 Months Ended
	Feb. 09, 2016	Aug. 17, 2015 USD ($) power_plant	Aug. 06, 2013 Defendant	Sep. 08, 2011 kV Customer	Dec. 31, 2015 USD ($)
ARIZONA PUBLIC SERVICE COMPANY
Superfund
Costs related to investigation and study under Superfund site					$ 2.0
Southwest Power Outage
Power outage capacity of transmission line that tripped out of service | kV				500
Period, after the transmission line went off-line, over which generation and transmission resources for the Yuma area were lost				10 minutes
Number of customers losing service in Yuma area | Customer				69,700
ARIZONA PUBLIC SERVICE COMPANY | Natural Gas Tolling Letter of Credit
Clean Air Act Citizen Lawsuit
Outstanding letters of credit					$ 6.7
ARIZONA PUBLIC SERVICE COMPANY | Contaminated groundwater wells
Superfund
Number of defendants against whom Roosevelt Irrigation District ("RID") filed lawsuit | Defendant			24
ARIZONA PUBLIC SERVICE COMPANY | Clean Air Act Citizen Lawsuit
Clean Air Act Citizen Lawsuit
Loss contingency, number of units | power_plant		2
Litigation settlement, percent of settlement		15.00%
Four Corners | Clean Air Act Citizen Lawsuit
Clean Air Act Citizen Lawsuit
Loss contingency, civil penalty amount		$ 1.5
Subsequent Event | Minimum | Loss of perishable inventory and sales
Southwest Power Outage
Time period a decision is reached after oral argument	30 days
Subsequent Event | Maximum | Loss of perishable inventory and sales
Southwest Power Outage
Time period a decision is reached after oral argument	60 days