Basis Of Presentation And Summary Of Significant Accounting Policies - Debt Issuance Costs (Details) - New Accounting Pronouncement, Early Adoption, Effect [Member] - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Other Noncurrent Assets [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Debt issuance cost	$ 176	$ 174
Long-term Debt [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Debt issuance cost	2,958	2,914
Previously Reported [Member] | Other Noncurrent Assets [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Debt issuance cost	186	184
Previously Reported [Member] | Long-term Debt [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Debt issuance cost	2,968	2,924
Effect Of Accounting Change [Member] | Other Noncurrent Assets [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Debt issuance cost	(10)	(10)
Effect Of Accounting Change [Member] | Long-term Debt [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Debt issuance cost	$ (10)	$ (10)