Supplementary Financial Information (Supplemental Cash Flow Information) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012		Sep. 30, 2013
Cash payments (receipts) related to:
Interest paid	$ 1,788	[1]	$ 1,901	[1]
Capitalized interest	(31)		(19)
Interest paid (net of capitalized interest)	1,757	[1]	1,882	[1]
Income Taxes Paid	83		134
Noncash investing and financing activities:
Effect of Parent's payment of interest, net of tax, on pushed down debt	30		21
Notes Issued	88		0
Construction expenditures	52	[2]	62	[2]
Contribution related to parent stock based compensation	6		1
Debt Assumed Related to Acquisition of Owner Participant Interest in Trust, Noncash	0		(45)
Effect of push down of debt from parent	0		(420)
Debt extension transactions	$ 0		$ (340)

[1] Net of amounts received under interest rate swap agreements.

[2] Represents end-of-period accruals.