Leases - Lease-related Assets and Liabilities recorded on the Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Assets
Operating lease assets	$ 51
Finance lease assets	141
Total lease assets	192
Liabilities
Current portion of operating lease liability	20
Current portion of finance lease liability	55	$ 17
Noncurrent portion of operating lease liability	38
Noncurrent portion of finance lease liability	75	$ 30
Long-term finance lease obligations	$ 188
Weighted-average remaining lease term
Weighted-average remaining lease term, finance leases	3 years 5 months 26 days
Weighted-average remaining lease term, operating leases	2 years 5 months 8 days
Weighted-average discount rate
Weighted-average discount rate, operating leases (percentage)	5.00%
Weighted-average discount rate, finance leases (percentage)	4.58%

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Leases, Right-Of-Use Assets [Abstract]

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Leases, Weighted Average Discount Rate [Abstract]

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Operating And Finance Lease, Liability

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Operating And Finance Lease, Right-Of-Use Asset

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Weighted Average Remaining Lease Term [Abstract]

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Present value of lessee's discounted obligation for lease payments from finance lease, classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
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Present value of lessee's discounted obligation for lease payments from finance lease, classified as noncurrent.

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Amount of lessee's right to use underlying asset under finance lease.

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Weighted average discount rate for finance lease calculated at point in time.

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Weighted average remaining lease term for finance lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of lessee's right to use underlying asset under operating lease.

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