Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2013 item	Dec. 31, 2012 item
Restricted Cash
Restricted cash	$ 619	$ 594
Restricted cash held in connection with the company's corporate credit card program	494	494
Restricted cash held in connection with the lease agreement for the company's Cambridge, Massachusetts facility	125	100
Receivables \| Credit risk concentration
Concentration of credit risk
Receivables/Sales (as a percent)	23.00%	41.00%
Number of customers	0	1
Receivables \| Credit risk concentration \| Customer product receivables
Concentration of credit risk
Accounts receivable	528	535
Receivables/Sales (as a percent)	44.00%	44.00%
Receivables \| Credit risk concentration \| Government grants
Concentration of credit risk
Accounts receivable	$ 552	$ 561
Receivables/Sales (as a percent)	46.00%	46.00%
Receivables \| Credit risk concentration \| REFABB grant with the Department of Energy
Concentration of credit risk
Receivables/Sales (as a percent)	56.00%

Represents information pertaining to number of customers whose account receivable is due from product sales.

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- Definition

Cash and equivalents the use of which, in whole or in part, is restricted for the long-term, held in connection with the entity's corporate credit card program.

+ References

No definition available.

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- Definition

Cash and equivalents the use of which, in whole or in part, is restricted for the long-term, held in connection with the lease agreements.

+ References

No definition available.

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 21

-Subparagraph (a)

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

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-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6404-108592

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13531-108611

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

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-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592

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- Definition

The total amount due to the entity within one year of the balance sheet date (or one operating cycle, if longer) from outside sources, including trade accounts receivable, notes and loans receivable, as well as any other types of receivables, net of allowances established for the purpose of reducing such receivables to an amount that approximates their net realizable value.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 3

-Subparagraph a

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.3,4)

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

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 4

-Article 5

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- Definition

Cash and equivalents whose use in whole or in part is restricted for the long-term, generally by contractual agreements or regulatory requirements.

+ 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 210.5-02.1)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

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-Article 5

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