Leases - Future Minimum Rental Commitments (Details) $ in Millions	Dec. 31, 2017 USD ($)
Leases [Abstract]
Noncancelable Operating Leases, Due 2018	$ 67
Minimum Lease Payments, Sale Leaseback Transactions, Next Twelve Months	666
Noncancelable Operating Leases, Due 2019	55
Minimum Lease Payments, Sale Leaseback Transactions, within Two Years	730
Noncancelable Operating Leases, Due 2020	54
Minimum Lease Payments, Sale Leaseback Transactions, within Three Years	734
Noncancelable Operating Leases, Due 2021	53
Minimum Lease Payments, Sale Leaseback Transactions, within Four Years	739
Noncancelable Operating Leases, Due 2022	49
Minimum Lease Payments, Sale Leaseback Transactions, within Five Years	745
Noncancelable Operating Leases, Due 2023 and thereafter	1,018
Minimum Lease Payments, Sale Leaseback Transactions, Thereafter	36,330
Noncancelable Operating Leases, Total minimum rental commitments	1,296
Minimum Lease Payments, Sale Leaseback Transactions	$ 39,944

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Amount of minimum lease payments for sale-leaseback transactions accounted for using the deposit method or as a financing.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 40
-Section 50
-Paragraph 2
-Subparagraph (a)
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Amount of minimum lease payments for sale-leaseback transactions accounted for using the deposit method or as a financing 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 of minimum lease payments for sale-leaseback transactions accounted for using the deposit method or as a financing 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.

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Amount of minimum lease payments for sale-leaseback transactions accounted for using the deposit method or as a financing 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.

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Amount of minimum lease payments for sale-leaseback transactions accounted for using the deposit method or as a financing 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.

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Amount of minimum lease payments for sale-leaseback transactions accounted for using the deposit method or as a financing 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.

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Amount of minimum lease payments for sale-leaseback transactions accounted for using the deposit method or as a financing 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.

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Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 55
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-SubTopic 20
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-Paragraph 2
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