Commitments and Contingencies (Future Minimum Capital Lease Payments) (Details) $ in Millions	Dec. 31, 2017 USD ($)
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2018	$ 29
2019	21
2020	12
2021	6
2022	1
Thereafter	3
Total	72
Less amount representing interest	(5)
Capital lease obligations	$ 67
Capital leases
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Weighted average interest rate	4.20%

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Amount of minimum lease payments for capital leases due in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84164817&loc=d3e45280-112737

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Amount of minimum lease payments for capital leases due in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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Amount of minimum lease payments for capital leases due in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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Amount of minimum lease payments for capital leases due in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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Amount of minimum lease payments for capital leases due in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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Amount of minimum lease payments for capital leases due after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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Amount necessary to reduce net minimum lease payments to present value for capital leases.

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Amount of minimum lease payments for capital leases net of executory costs, which include amounts paid by the lessee to the lessor for insurance, maintenance and taxes.

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Present value of minimum lease payments for capital leases net of executory costs, including amounts paid by the lessee to the lessor for insurance, maintenance and taxes.

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Weighted average interest rate of debt outstanding.

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