Fair Value of Financial Instruments (Details) - Fair value measurements determined on a nonrecurring basis - Fair value inputs, Level 2 - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Carrying Amount
Fair value disclosure
Long-term debt, excluding finance lease and other obligations	$ 34,911	$ 35,260
Interest rate swap contracts	71	0
Fair Value
Fair value disclosure
Long-term debt, excluding finance lease and other obligations	$ 35,739	32,915
Interest rate swap contracts		$ 0

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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-Section 50
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226000-175313

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Balance Type:	credit
Period Type:	instant