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- Definition

Indicates (true false) whether practical expedients are elected for not reassessing whether any expired or existing contract is or contains lease, lease classification for expired or existing lease, and initial direct cost for any existing lease.

+ References

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

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
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- Definition

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.

+ References

No definition available.

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- Definition

Present value of lessee's discounted obligation for lease payments from operating lease.

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- Definition

Present value of lessee's discounted obligation for lease payments from operating lease, classified as current.

+ References

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- Definition

Indicates line item in statement of financial position that includes current operating lease liability.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Present value of lessee's discounted obligation for lease payments from operating lease, classified as noncurrent.

+ References

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- Definition

Amount of lessee's right to use underlying asset under operating lease.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The cumulative amount of the reporting entity's undistributed earnings or deficit.

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No definition available.

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Minimum period for maturity dates relating to short-term investments, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

The amount of the carrying value for the remaining option payment proceeds to be recognized as a contract liability until the title has been transferred to the buyer or the option agreement has been terminated.

+ References

No definition available.

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Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Significant Accounting Policies
Minimum period for maturity dates for short-term investments	90 days
Accumulated deficit	$ (438,336)		$ (435,684)
Lease accounting
Operating lease liabilities	163
Right of use operating assets	$ 63
Lease, Practical Expedients, Package [true false]	true
Operating Lease, Liability, Current	$ 100
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Accrued Liabilities, Current
Operating Lease, Liability, Noncurrent	$ 63
Other Assets [Member]
Lease accounting
Right of use operating assets	163
Other Current Assets [Member]
Lease accounting
Right of use operating assets	$ 100
Minimum
Lease accounting
Lessee, Operating Lease, Renewal Term	8 months 12 days
Maximum
Lease accounting
Lessee, Operating Lease, Renewal Term	2 years 8 months 12 days
Guadalupe De Los Reyes, Mexico \| Option Agreement Two
Revenue recognition
Value of carrying value for option payment proceeds to be recognized as contract liability	$ 0
Accounting Standards Update 2016-02 \| Restatement adjustment
Lease accounting
Operating lease liabilities		$ 186
Right of use operating assets		$ 186