Other Long-Term Liabilities (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Dec. 31, 2014	Sep. 30, 2014	Aug. 09, 2013
Other Long-Term Liabilities
Interest rate swap liabilities	1,532	$ 1,348
EnergyRight® purchase obligation	215	215
Percentage of membership interests issued			100.00%
Currency swap liabilities	23	15
Total other long-term liabilities	2,194us-gaap_OtherLiabilitiesNoncurrent	1,962us-gaap_OtherLiabilitiesNoncurrent
Membership interests of VIE subject to mandatory redemption, interest rate, stated percentage			7.00%
Membership interests of VIE subject to mandatory redemption	50	50	40
SCCG balloon payment			4tve_SCCGballoonpayment
Energy Right Program
Other Long-Term Liabilities
Number of days in default	180 days
Other Noncurrent Liabilities [Member]
Other Long-Term Liabilities
Interest rate swap liabilities	1,532	1,348
Environmental agreements liability	92	108
EnergyRight® purchase obligation	153	152
Commodity contract derivative liabilities	32	17
Membership interests of VIE subject to mandatory redemption	37	37
Commodity swap derivative liabilities	13	14
Currency swap liabilities	23	15
Other	312	271
Accounts Payable and Accrued Liabilities [Member]
Other Long-Term Liabilities
EnergyRight® purchase obligation	38	38
Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount, Current	2	$ 2

Carrying amount as of the balance sheet date of the liability arising from commodity contracts such as futures contracts tied to the movement of a particular commodity, which are expected to be converted into cash or otherwise disposed of after a year or beyond the normal operating cycle, if longer.

No definition available.