Commitments - Estimated Long-term obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2013
Minimum Lease Payments, Operating Leases [Abstract]
2016	$ 121
2017	103
2018	81
2019	61
2020	53
2021 and thereafter	706
Total	1,125
Alabama Power [Member]
Minimum Lease Payments, Operating Leases [Abstract]
2016	19
2017	13
2018	9
2019	9
2020	9
2021 and thereafter	13
Total	72
Georgia Power [Member]
Minimum Lease Payments, Operating Leases [Abstract]
2016	23
2017	18
2018	12
2019	8
2020	7
2021 and thereafter	16
Total	84
2016	246
2017	224
2018	217
2019	221
2020	214
2021 and thereafter	1,819
Total	2,941
Minimum Lease Payments, Capital Leases [Abstract]
Capital Leases, Future Minimum Payments, Lesser Of Fair Value and Present Value	$ 149
Period Of Service For Gas Transportation Supplier	1 year
Gulf Power [Member]
Minimum Lease Payments, Operating Leases [Abstract]
2016	$ 10
2017	7
2018	4
Total	21
Railcars [Member] | Alabama Power [Member]
Minimum Lease Payments, Operating Leases [Abstract]
2016	13
2017	8
2018	5
2019	5
2020	5
2021 and thereafter	13
Total	49
Vehicles And Other [Member] | Alabama Power [Member]
Minimum Lease Payments, Operating Leases [Abstract]
2016	6
2017	5
2018	4
2019	4
2020	4
2021 and thereafter	0
Total	23
Barges and Rail Cars [Member]
Minimum Lease Payments, Operating Leases [Abstract]
2016	40
2017	25
2018	14
2019	6
2020	6
2021 and thereafter	16
Total	107
Barges and Rail Cars [Member] | Georgia Power [Member]
Minimum Lease Payments, Operating Leases [Abstract]
2016	15
2017	10
2018	5
2019	1
2020	1
2021 and thereafter	3
Total	35
Barges and Rail Cars [Member] | Gulf Power [Member]
Minimum Lease Payments, Operating Leases [Abstract]
2016	9
2017	6
2018	4
Total	19
Other Lease Payments [Member]
Minimum Lease Payments, Operating Leases [Abstract]
2016	81
2017	78
2018	67
2019	55
2020	47
2021 and thereafter	690
Total	1,018
Other Lease Payments [Member] | Georgia Power [Member]
Minimum Lease Payments, Operating Leases [Abstract]
2016	8
2017	8
2018	7
2019	7
2020	6
2021 and thereafter	13
Total	49
Other Lease Payments [Member] | Gulf Power [Member]
Minimum Lease Payments, Operating Leases [Abstract]
2016	1
2017	1
2018	0
Total	2
Purchased Power [Member]
Recorded Unconditional Purchase Obligation, Fiscal Year Maturity Schedule [Abstract]
2016	233
2017	242
2018	246
2019	249
2020	246
2021 and thereafter	1,291
Total	2,507
Purchased Power [Member] | Alabama Power [Member]
Recorded Unconditional Purchase Obligation, Fiscal Year Maturity Schedule [Abstract]
2016	39
2017	40
2018	41
2019	43
2020	44
2021 and thereafter	93
Total	300
Purchased Power [Member] | Gulf Power [Member]
Recorded Unconditional Purchase Obligation, Fiscal Year Maturity Schedule [Abstract]
2016	79
2017	79
2018	79
2019	79
2020	79
2021 and thereafter	191
Total	586
Other Lease Payments [Member]
Recorded Unconditional Purchase Obligation, Fiscal Year Maturity Schedule [Abstract]
2016	10
2017	8
2018	7
2019	8
2020	4
2021 and thereafter	47
Total	84
Affiliate Capital Lease PPA [Member] | Georgia Power [Member]
Minimum Lease Payments, Capital Leases [Abstract]
2016	22
2017	22
2018	22
2019	23
2020	23
2021 and thereafter	227
Total	339
Less: amounts representing executory costs	54
Net minimum lease payments	285
Less: amounts representing interest	84
Present value of net minimum lease payments	201
Affiliate Operating Lease PPA [Member] | Georgia Power [Member]
Minimum Lease Payments, Operating Leases [Abstract]
2016	99
2017	71
2018	62
2019	63
2020	64
2021 and thereafter	538
Total	897
Non-Affiliate Operating Lease PPA [Member] | Georgia Power [Member]
Minimum Lease Payments, Operating Leases [Abstract]
2016	115
2017	123
2018	126
2019	127
2020	123
2021 and thereafter	1,007
Total	1,621
Minimum Lease Payments, Capital Leases [Abstract]
Biomass PPAs Amount	304
Plant Vogtle Units 1 and 2 [Member] | Georgia Power [Member]
Minimum Lease Payments, Operating Leases [Abstract]
2016	10
2017	8
2018	7
2019	8
2020	4
2021 and thereafter	47
Total	$ 84
Plant McIntosh [Member] | Georgia Power [Member]
Minimum Lease Payments, Capital Leases [Abstract]
Period Of Service For Gas Transportation Supplier		15 years