Fair Value Measurements and Financial Instruments - Schedule of financial instruments where the carrying amounts and fair values differ (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Carrying Value
Fair value of financial instrument
Current portion of long-term debt	$ 0	$ 299
Long-term debt	5,659	5,667
Fair Value \| Fair Value, Inputs, Level 2
Fair value of financial instrument
Current portion of long-term debt	0	301
Long-term debt	$ 5,871	$ 6,267

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents the amount of short-term debt existing as of the balance sheet date.

No definition available.

Name:	us-gaap_ShorttermDebtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant