XML 48 R37.htm IDEA: XBRL DOCUMENT v3.7.0.1
Income taxes (Valuation and Qualifying Accounts) (Details) - USD ($)
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Income Taxes Valuation And Qualifying Accounts Details    
Balance at Beginning of Period $ 4,144,741 $ 4,078,470
Charged to Cost and Expenses (81,304) 66,271
Write-offs
Other Charges
Balance at End of Period $ 4,063,436 $ 4,144,741