Long-Term Debt (Long-Term Debt) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Dec. 31, 2014
Debt Instrument [Line Items]
Long-term debt, beginning balance	$ 9,781
Payments and Retirements	(129)
New Borrowings	3
Long-term debt, ending balance	9,655
Less: Debt (Discount)/Premium	2		3
Less: Current Portion	(193)		(298)
Principal Outstanding	9,464		9,486
Weighted average interest rate	7.66%	[1]
Senior Unsecured Debt [Member]
Debt Instrument [Line Items]
Long-term debt, beginning balance	9,750
Payments and Retirements	(128)
Long-term debt, ending balance	9,622
Weighted average interest rate	7.68%	[1]
Other Secured Debt [Member]
Debt Instrument [Line Items]
Long-term debt, beginning balance	23
Payments and Retirements	(1)
New Borrowings	3
Long-term debt, ending balance	25
Weighted average interest rate	3.38%	[1]
Rural Utilities Service Loan Contracts [Member]
Debt Instrument [Line Items]
Long-term debt, beginning balance			8
Long-term debt, ending balance	$ 8		$ 8
Weighted average interest rate	6.15%	[1]

[1] Interest rate includes amortization of debt issuance costs and debt premiums or discounts. The interest rates at March 31, 2015 represent a weighted average of multiple issuances.