Debt (Details 1) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Debt Instrument [Line Items]
Debt partial extinguishment	$ 0	$ 0	$ 2,467	$ 0
Debt discount amortization			6,353	6,376
Debt financing amortization			727	695
Convertible Notes Payable
Debt Instrument [Line Items]
Interest expense	4,345	3,780	14,740	11,114
Convertible Note 2019 \| Convertible Notes Payable
Debt Instrument [Line Items]
Interest expense	644	1,348	2,870	4,043
Debt partial extinguishment	0	0	2,467	0
Debt discount amortization	1,192	2,193	5,102	6,376
Debt financing amortization	130	239	576	695
Term Loan 2021 \| Convertible Notes Payable
Debt Instrument [Line Items]
Interest expense	659	0	800	0
Debt discount amortization	22	0	36	0
Debt financing amortization	30	0	47	0
Convertible Note 2023 \| Convertible Notes Payable
Debt Instrument [Line Items]
Interest expense	889	0	1,523	0
Debt discount amortization	717	0	1,215	0
Debt financing amortization	$ 62	$ 0	$ 104	$ 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
-Paragraph 1A
-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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-Name Accounting Standards Codification
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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
-Name Accounting Standards Codification
-Topic 225
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