Commodity And Other Derivative Contractual Assets And Liabilities (Financial Statement Effects of Derivatives) (Details) - USD ($) $ in Millions		3 Months Ended		5 Months Ended	9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	May. 02, 2014
Derivatives, Fair Value [Line Items]
Net Settlement Liability, Positions Terminated By Counterparties								$ 1,108
Realized Gain (Loss) On Terminated Interest Rate Derivatives	[1]	$ 0	$ 0		$ 0	$ (1,225)
Realized Gain (Loss) On Terminated Commodity Related Derivatives					0	117
Net Liability, Accounts Payable Related To Matured Interest Rate Swaps Secured By First-Lien Secured Interest		127			127
Liabilities Subject To Compromise, Liability Under Terminated Agreements, Net		1,235			1,235		$ 1,235
Liability adjustment arising from termination of interest rate swaps (Note 13)		0	$ 0	$ 277	0	277
Commodity contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative assets: Amounts Presented in Balance Sheet		423			423		497
Derivative liabilities, Fair Value, Gross Liability		(164)			(164)		(317)
Derivative asset, Fair Value, Net		407			407		497
Derivative liabilities, Fair Value, Net		(148)			(148)		(317)
Commodity contracts [Member] | Current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative assets: Amounts Presented in Balance Sheet		393			393		492
Derivative liabilities, Fair Value, Gross Asset		0			0		0
Commodity contracts [Member] | Noncurrent assets [Member]
Derivatives, Fair Value [Line Items]
Derivative assets: Amounts Presented in Balance Sheet		14			14		5
Derivative liabilities, Fair Value, Gross Asset		16			16		0
Commodity contracts [Member] | Current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Fair Value, Gross Liability		0			0		0
Derivative liabilities, Fair Value, Gross Liability		(160)			(160)		(316)
Commodity contracts [Member] | Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Fair Value, Gross Liability		0			0		0
Derivative liabilities, Fair Value, Gross Liability		$ (4)			$ (4)		$ (1)
Texas Competitive Electric Holdings Company LLC | Commodity contracts [Member]
Derivatives, Fair Value [Line Items]
Realized Gain (Loss) On Terminated Commodity Related Derivatives						117
Texas Competitive Electric Holdings Company LLC | Interest rate swaps [Member]
Derivatives, Fair Value [Line Items]
Realized Gain (Loss) On Terminated Interest Rate Derivatives						$ (1,225)

[1] See Note 13.