Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Accounts Receivable (Details)

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Summary of Significant Accounting Policies - Accounts Receivable (Details) (USD $)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Allowance for Doubtful Accounts Receivable [Roll Forward]      
Allowance for doubtful accounts, beginning of period $ 1,174,458 $ 1,135,391 $ 1,677,278
Charges to costs and expenses 502,067 148,773 24,374
Account write-offs and other (157,437) (109,706) (566,261)
Allowance for doubtful accounts, end of period $ 1,519,088 $ 1,174,458 $ 1,135,391
Minimum
     
Allowance for Doubtful Accounts Receivable [Roll Forward]      
Accounts receivable retainage 5.00%    
Maximum
     
Allowance for Doubtful Accounts Receivable [Roll Forward]      
Accounts receivable retainage 10.00%