Leases (Schedule of Future Minimum Lease Payments for Capital Leases) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Leases [Abstract]
2013	$ 43
2014	42
2015	40
2016	40
2017	40
Later years	288
Sublease income	0
Minimum lease commitments	493
Less amounts representing interest	(249)
Present value of net minimum lease obligations	$ 244

Amount of minimum lease payments for capital leases.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 50

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Amount of minimum lease payments maturing in the next fiscal year following the latest fiscal year for capital leases.

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Amount of minimum lease payments maturing in the fifth fiscal year following the latest fiscal year for capital leases.

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Amount of minimum lease payments maturing in the forth fiscal year following the latest fiscal year for capital leases.

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Amount of minimum lease payments maturing in the third fiscal year following the latest fiscal year for capital leases.

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Amount of minimum lease payments maturing in the second fiscal year following the latest fiscal year for capital leases.

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Amount of minimum lease payments maturing after the fifth fiscal year following the latest fiscal year for capital leases.

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

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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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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Minimum payments receivable in the future under noncancelable subleases.

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