Income Taxes - Accrued Interest for Unrecognized Tax Benefits (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of Accrued Interest For Unrecognized Tax Benefits [Roll Forward]
Interest accrued at beginning of year	$ 1,000,000	$ 10,000,000	$ 29,000,000
Interest reclassified due to settlements	0	(9,000,000)	(24,000,000)
Interest accrued during the period	0	0	5,000,000
Balance at end of year	1,000,000	1,000,000	10,000,000
Alabama Power [Member]
Reconciliation of Accrued Interest For Unrecognized Tax Benefits [Roll Forward]
Interest accrued at beginning of year	0	1,900,000	1,500,000
Interest reclassified due to settlements	0	(1,900,000)	0
Interest accrued during the period	0	0	400,000
Balance at end of year	0	0	1,900,000
Georgia Power [Member]
Reconciliation of Accrued Interest For Unrecognized Tax Benefits [Roll Forward]
Interest accrued at beginning of year	0	6,000,000	27,000,000
Interest reclassified due to settlements	0	(6,000,000)	(24,000,000)
Interest accrued during the period	0	0	3,000,000
Balance at end of year	0	0	6,000,000
Mississippi Power [Member]
Reconciliation of Accrued Interest For Unrecognized Tax Benefits [Roll Forward]
Interest accrued at beginning of year	772,000	680,000	413,000
Interest accrued during the period	399,000	92,000	267,000
Balance at end of year	$ 1,171,000	$ 772,000	$ 680,000