Contingencies and Regulatory Matters Retail Regulatory Matters (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Loss Contingencies [Line Items]
Other Regulatory Liabilities, Current	$ 116,000,000	$ 92,000,000
Alabama Power [Member]
Loss Contingencies [Line Items]
Under recovered rate CNP environmental balance	13,000,000	7,000,000
Under Recovered Rate Cnp Balance	23,000,000	18,000,000
Other Regulatory Liabilities, Current	36,000,000	37,000,000
Deferred Over Recovered Regulatory Clause Revenues	0	15,000,000
Accumulated reserve balance for future storms	91,000,000	96,000,000
Fuel Recovery Clause [Member] | Alabama Power [Member]
Loss Contingencies [Line Items]
Other Regulatory Liabilities, Current	22,000,000	27,000,000
Deferred Over Recovered Regulatory Clause Revenues	$ 0	$ 15,000,000