Long-Term Debt and Liquidity Matters Estimated Fair Value of Long-Term Debt (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Estimated fair value of long-term debt, including current maturities
Debt and Capital Lease Obligations	$ 3,407	$ 3,337
Long-term Debt, Fair Value	3,787	3,579
Pinnacle West
Estimated fair value of long-term debt, including current maturities
Debt and Capital Lease Obligations	125	125
Long-term Debt, Fair Value	125	125
Arizona Public Service Company
Estimated fair value of long-term debt, including current maturities
Debt and Capital Lease Obligations	3,282	3,212
Long-term Debt, Fair Value	$ 3,662	$ 3,454