Summary of Significant Accounting Policies Contractual Future Minimum Lease Receipt Table (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014
Summary of Significant Accounting Policies [Abstract]
Operating Leases, Future Minimum Payments Receivable, Current	$ 561
Operating Leases, Future Minimum Payments Receivable, in Two Years	495
Operating Leases, Future Minimum Payments Receivable, in Three Years	433
Operating Leases, Future Minimum Payments Receivable, in Four Years	396
Operating Leases, Future Minimum Payments Receivable, in Five Years	357
Operating Leases, Future Minimum Payments Receivable, Thereafter	1,380
Operating Leases, Future Minimum Payments Receivable	$ 3,622

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Future minimum rental payments in aggregate as of the balance sheet date under operating leases.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6454179&loc=d3e41551-112718

+ Details

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- Definition

Future rental payments receivable within one year of the balance sheet date under an operating lease.

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+ Details

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- Definition

Future rental payments receivable within the fifth year from the balance sheet date under an operating lease.

+ References

+ Details

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- Definition

Future rental payments receivable within the fourth year from the balance sheet date under an operating lease.

+ References

+ Details

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- Definition

Future rental payments receivable within the third year from the balance sheet date under an operating lease.

+ References

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- Definition

Future rental payments receivable within the second year from the balance sheet date under an operating lease.

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- Definition

Future minimum lease payments receivable under operating leases for periods greater than five years following the balance sheet date.

+ References

+ Details

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