Marketable Securities (Narrative) (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Loss	$ 73,000	$ 0
Available-For-Sale Securities Number of Securities Owned	41
Available-For-Sale Securities Number Of Securities Owned Unrealized Losses	38
Available-for-sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Loss	100,000
Auction Rate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Sale proceeds	1,800,000
Available-for-sale Securities, Gross Realized Gains	600,000
Available-for-sale Securities, Gross Unrealized Loss	$ 0	$ 0

Available-For-Sale securities number of securities owned during period.

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- Definition

Available for sale Securities Number Of Securities Owned Unrealized Losses.

+ References

No definition available.

+ Details

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- Definition

This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27357-111563

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- Definition

The total amount of proceeds received for the sale of securities, categorized neither as held-to-maturity nor trading securities, during the reporting period.

+ References

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- Definition

Amount of unrealized loss before deducting unrealized gain on investments in available-for-sale securities.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

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