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 Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

+ References+ Details

This item represents the aggregate carrying amount of all cost-method investments as reported on or included in the balance sheet. The original cost of the investments may differ from the aggregate carrying amount disclosed due to various adjustments such as: (i) dividends received in excess of earnings after the date of investment that are considered a return of investment and therefore recorded as reductions to cost of the investment, or (ii) a series of operating losses of an investee or other factors which may indicate that a decrease in value of the investment has occurred which is other than temporary and accordingly such decrease in value has been recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.12)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 325

-SubTopic 20

-Section 35

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6383889&loc=d3e40346-111594

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

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 03-1

-Paragraph 22

-Subparagraph a

-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 AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 18

-Paragraph 6

-Subparagraph a

-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 FASB

-Name Accounting Standards Codification

-Topic 325

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6872867&loc=d3e40691-111596

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 18

-Subparagraph a

-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.

+ Details

- Definition

The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting.

+ References+ Details

Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013 Item	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Money market funds	Dec. 31, 2012 Money market funds	Jun. 30, 2013 Corporate notes, bonds and commercial paper	Dec. 31, 2012 Corporate notes, bonds and commercial paper	Jun. 30, 2013 Recurring basis Total	Dec. 31, 2012 Recurring basis Total	Jun. 30, 2013 Recurring basis Total Money market funds	Dec. 31, 2012 Recurring basis Total Money market funds	Jun. 30, 2013 Recurring basis Total Corporate notes, bonds and commercial paper	Dec. 31, 2012 Recurring basis Total Corporate notes, bonds and commercial paper	Jun. 30, 2013 Recurring basis Quoted Market Prices in Active Markets (Level 1)	Dec. 31, 2012 Recurring basis Quoted Market Prices in Active Markets (Level 1)	Jun. 30, 2013 Recurring basis Quoted Market Prices in Active Markets (Level 1) Money market funds	Dec. 31, 2012 Recurring basis Quoted Market Prices in Active Markets (Level 1) Money market funds	Jun. 30, 2013 Recurring basis Quoted Market Prices in Active Markets (Level 1) Corporate notes, bonds and commercial paper	Dec. 31, 2012 Recurring basis Quoted Market Prices in Active Markets (Level 1) Corporate notes, bonds and commercial paper	Jun. 30, 2013 Recurring basis Significant Other Observable Inputs (Level 2)	Dec. 31, 2012 Recurring basis Significant Other Observable Inputs (Level 2)	Jun. 30, 2013 Recurring basis Significant Other Observable Inputs (Level 2) Money market funds	Dec. 31, 2012 Recurring basis Significant Other Observable Inputs (Level 2) Money market funds	Jun. 30, 2013 Recurring basis Significant Other Observable Inputs (Level 2) Corporate notes, bonds and commercial paper	Dec. 31, 2012 Recurring basis Significant Other Observable Inputs (Level 2) Corporate notes, bonds and commercial paper	Jun. 30, 2013 Recurring basis Significant Unobservable Inputs (Level 3)	Dec. 31, 2012 Recurring basis Significant Unobservable Inputs (Level 3)	Jun. 30, 2013 Recurring basis Significant Unobservable Inputs (Level 3) Money market funds	Dec. 31, 2012 Recurring basis Significant Unobservable Inputs (Level 3) Money market funds	Jun. 30, 2013 Recurring basis Significant Unobservable Inputs (Level 3) Corporate notes, bonds and commercial paper	Dec. 31, 2012 Recurring basis Significant Unobservable Inputs (Level 3) Corporate notes, bonds and commercial paper	Mar. 31, 2013 Nonrecurring basis
Financial assets subject to fair value measurements and the necessary disclosures
Number of pricing sources		2
Total available-for-sale securities	$ 193,724	$ 193,724		$ 183,915	$ 134,860	$ 126,570	$ 58,864	$ 57,345	$ 193,724	$ 183,915	$ 134,860	$ 126,570	$ 58,864	$ 57,345	$ 134,860	$ 126,570	$ 134,860	$ 126,570	$ 0	$ 0	$ 58,864	$ 57,345	$ 0	$ 0	$ 58,864	$ 57,345	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Investment in non-marketable equity securities
Carrying value																																	2,000
Impairment of investment in non-marketable equity security	$ 1,400	$ 1,400	$ 0