Schedule II - Valuation and qualifying accounts (Details) - USD ($)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for doubtful accounts
Activity in valuation and qualifying accounts
Balance at beginning of period	$ 92,354	$ 108,765	$ 169,674
Additions charged to expenses	62,681	8,388	46,652
Deductions	(23,965)	(24,799)	(107,561)
Balance at end of period	131,070	92,354	108,765
Deferred tax valuation allowance
Activity in valuation and qualifying accounts
Balance at beginning of period	20,561,516	28,475,080	29,416,464
Additions charged to expenses	626,122	653,947	843,479
Deductions	(20,258,937)	(8,567,511)	(1,784,863)
Balance at end of period	$ 928,701	$ 20,561,516	$ 28,475,080

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

+ Details

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- Definition

Amount of increase in the allowances and reserves, which consist of the valuation and qualifying accounts that are either netted against the cost of an asset or that reflect a liability established to represent expected future costs, from charges to costs and expenses.

+ References

+ Details

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- Definition

Total of the deductions in a given period to 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, representing receivables written off as uncollectible and portions of the reserves utilized, respectively.

+ References

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