Notes Payable (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2015	Sep. 30, 2015
Contractual interest	$ 151	$ 502
Accelerated interest due to the conversion of convertible senior notes into common stock	200	763
Amortization of debt issuance costs	80	292
Accelerated amortization of debt issuance cost due to the conversion of convertible senior notes into common stock	68	302
Total interest expense on the convertible senior notes	$ 499	$ 1,859

Amount of noncash expense included in interest expense to allocate debt discount and premium, and the costs to issue debt and obtain financing over the related debt instruments. Alternate captions include noncash interest expense.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

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The amount of contractual interest expense on prepetition liabilities not included in the statement of operations.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 852

-SubTopic 10

-Section 55

-Paragraph 3

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Interest and debt related expenses associated with nonoperating financing activities of the entity.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 20

-Section 50

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Amount of the cost of borrowed funds accounted for as interest expense for debt.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.8)

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Write-off of amounts previously capitalized as debt issuance cost in an extinguishment of debt.

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