Leases - Maturities of Operating and Financing Lease Liabilities (Details) $ in Millions	Dec. 31, 2019 USD ($)
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020	$ 0
2021	1
2022	0
2023	1
2024	0
Remainder	6
Total lease payments	8
Less: Interest	(4)
Present value of lease liabilities	4
Operating lease, payments due, related to options to extend	2
Finance Lease, Liability, Payment, Due [Abstract]
2020	4
2021	4
2022	4
2023	4
2024	5
Remainder	31
Total lease payments	52
Less: Interest	(27)
Present value of lease liabilities	25
Finance lease, liability, payments due, principal amounts	25
Finance lease, liability, payments due, executory costs	9
Current finance lease liabilities	1
Operating And Finance Lease, Liabilities, Payments Due [Abstract]
2020	4
2021	5
2022	4
2023	5
2024	5
Remainder	37
Total lease payments	60
Less: Interest	(31)
Present value of lease liabilities	$ 29

Finance Lease, Liability, Payments, Due, Executory Costs

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Finance Lease, Liability, Payments, Due, Principal Amount

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Lessee, Operating Lease, Payments, Due, Related To Options To Extend

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Operating And Finance Lease, Liabilities, Payments, Due Year Three

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Present value of lessee's discounted obligation for lease payments from finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918701-209980

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977

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Amount of lessee's undiscounted obligation for lease payments for finance lease, due in next fiscal year following latest fiscal year.

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Amount of lessee's undiscounted obligation for lease payments for finance lease, due in fifth fiscal year following latest fiscal year.

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Amount of lessee's undiscounted obligation for lease payments for finance lease, due in fourth fiscal year following latest fiscal year.

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Amount of lessee's undiscounted obligation for lease payments for finance lease, due in third fiscal year following latest fiscal year.

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Amount of lessee's undiscounted obligation for lease payments for finance lease, due in second fiscal year following latest fiscal year.

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Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments for finance lease.

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Amount of lessee's undiscounted obligation for lease payments for operating lease.

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Amount of lessee's undiscounted obligation for lease payments for operating lease, due after fifth fiscal year following latest fiscal year.

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Amount of lessee's undiscounted obligation for lease payments for operating lease, due in third fiscal year following latest fiscal year.

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Amount of lessee's undiscounted obligation for lease payments for operating lease, due in second fiscal year following latest fiscal year.

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Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments for operating lease.

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