Fair Value (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Fair Value [Abstract]
Transfers from Level I to Level II	$ 0	$ 0
Transfers from Level II to Level I	0	0
Number Of Assets Measured At Fair Value On Nonrecurring Basis	0	0
Number Of Liabilities Measured At Fair Value On Nonrecurring Basis	$ 0	$ 0

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Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bb)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

+ Details

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- Definition

Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

+ References

+ Details

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- Definition

Number Of Assets Measured At Fair Value On Nonrecurring Basis

+ References

No definition available.

+ Details

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- Definition

Number Of Liabilities Measured At Fair Value On Nonrecurring Basis

+ References

No definition available.

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