Income taxes (Valuation and Qualifying Accounts) (Details) (Deferred tax asset valuation allowance, USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Deferred tax asset valuation allowance
Balance at Beginning of Period	$ 3,882,154	$ 3,817,895
Charged to Cost and Expenses	196,316	64,259
Write-offs
Other Charges
Balance at End of Period	$ 4,078,470	$ 3,882,154

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No definition available.

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- Definition

Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 09

-Article 12

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- Definition

+ References

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- Definition

+ References

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