This item represents investments in debt securities which are categorized as held-to-maturity and that have scheduled maturities within one year of the balance sheet date or the normal operating cycle, whichever is longer; such investments are measured at amortized cost (carrying value). The held-to-maturity category is for those securities that the Entity has the positive intent and ability to hold until maturity.

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

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Chapter 3

-Section A

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

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-Paragraph 4

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

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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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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

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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.

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

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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.

Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

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+ Details

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents notes payable as of the balance sheet date.

+ References+ Details

Fair Value Of Financial Instruments And Investments (Narrative) (Details) (USD $)								12 Months Ended
	Mar. 31, 2012	Mar. 31, 2012 Senior Convertible Notes Due 2018 [Member]	Feb. 04, 2011 Level 3 [Member] Senior Convertible Notes Due 2018 [Member]	Mar. 31, 2012 Certificates Of Deposit [Member]	Dec. 31, 2011 Certificates Of Deposit [Member]	Mar. 31, 2012 Certificates Of Deposit [Member] Level 3 [Member]	Dec. 31, 2011 Certificates Of Deposit [Member] Level 3 [Member]	Dec. 31, 2012 Maximum [Member]	Dec. 31, 2011 Maximum [Member]
Fair Value Of Financial Instruments [Line Items]
Convertible Notes at fair value			$ 169,800,000
Carrying value		177,100,000
Fair value		105,000,000
Senior convertible notes, interest rate	4.75%	4.75%
Held To Maturity Securities Current, Fair Value				48,408,000	55,694,000
Certificates of deposit held-to-maturity, estimated fair value				48,408,000	55,694,000
Certificates of deposit held-to-maturity, cost				$ 48,408,000	$ 55,694,000
Certificates of deposit maturity period, years								1 year	1 year