Basis of Presentation and Summary of Significant Accounting Policies - Contract Assets and Liabilities (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Current portion of contract assets	$ 10	$ 22
Current portion of contract liabilities	513	461
Non-current portion of contract liabilities	79	$ 85
Revenue recognized that was included in contract liabilities	320
Remaining performance obligations	$ 3,100

No definition available.

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Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
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-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130533-203044

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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as noncurrent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130532-203044

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Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

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Total carrying amount of consideration received or receivable as of the balance sheet date on potential earnings that were not recognized as revenue or other forms of income in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer.

+ References

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-Publisher FASB
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Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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