Debt (Details 1) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	6 Months Ended
Apr. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Debt Instrument [Line Items]
Debt partial extinguishment		$ 2,467	$ 0	$ 2,467	$ 0
Debt discount amortization				4,422	4,183
Debt financing amortization				505	456
Convertible Notes Payable
Debt Instrument [Line Items]
Interest expense		6,453	3,705	10,395	7,334
Convertible Note 2019
Debt Instrument [Line Items]
Debt partial extinguishment	$ 75,100
Convertible Note 2019 \| Convertible Notes Payable
Debt Instrument [Line Items]
Interest expense		878	1,347	2,226	2,695
Debt partial extinguishment		2,467	0	2,467	0
Debt discount amortization		1,571	2,126	3,910	4,183
Debt financing amortization		191	232	446	456
Term Loan 2021 \| Convertible Notes Payable
Debt Instrument [Line Items]
Interest expense		141	0	141	0
Debt discount amortization		14	0	14	0
Debt financing amortization		17	0	17	0
Convertible Note 2023 \| Convertible Notes Payable
Debt Instrument [Line Items]
Interest expense		634	0	634	0
Debt discount amortization		498	0	498	0
Debt financing amortization		$ 42	$ 0	$ 42	$ 0

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. 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
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
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-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 3: 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)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Amount of amortization expense attributable to debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
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-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Gross amount of debt extinguished.

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

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, excluding amortization of debt discount (premium) and financing costs.

+ References

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