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-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

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+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12A
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+ References

No definition available.

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Revenue - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
Revenue - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation Of Revenue [Line Items]
Contract with Customer, Performance Obligation Satisfied in Previous Period	$ 9		$ 9
December 31 2018 [Member]
Disaggregation Of Revenue [Line Items]
Contract with Customer, Liability, Revenue Recognized	54		$ 296
March 31 2019 [Member]
Disaggregation Of Revenue [Line Items]
Contract with Customer, Liability, Revenue Recognized	$ 214
Other [Member] \| Maximum [Member]
Disaggregation Of Revenue [Line Items]
Revenue, Percentage of Total Revenue	5.00%	5.00%	5.00%	5.00%