Fair Value Measurements Fair Value Measurements (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
Mar. 31, 2013	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Equity, Level 1 to Level 2 Transfers, Amount	$ 0
Number Of Available For Sale Equity Securities Continuous Unrealized Loss Position	24
Fair Value, Level 1 to level 2 Transfers, Amount		0
Fair Value,Transfers out of Level 3	0	0
Fair Value, Transfers Into Level 3	$ 0	$ 0

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Amount of transfers of financial instruments classified in shareholders' equity 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

Description of the transfers of liabilities measured on a recurring basis out of Level 2 and into Level 1 of the fair value hierarchy.

+ References

+ Details

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- Definition

Transfers into assets measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period.

+ 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 (c)(3)

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

+ Details

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- Definition

Transfers out of assets measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period.

+ 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 (c)(3)

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

+ Details

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- Definition

Number Of Available For Sale Equity Securities Continuous Unrealized Loss Position

+ References

No definition available.

+ Details

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