Annual report pursuant to Section 13 and 15(d)

Consolidated Balance Sheets (Parenthetical)

v3.8.0.1
Consolidated Balance Sheets (Parenthetical) - USD ($)
Dec. 31, 2017
Dec. 31, 2016
Statement of Financial Position [Abstract]    
Trade receivables, allowance for doubtful accounts $ 2,389,566.38 $ 2,988,634.79
Common Stock, Par or Stated Value Per Share $ 0.01 $ 0.01
Common stock, shares authorized 60,000,000 60,000,000
Common stock, shares issued 38,656,505 37,939,032
Treasury stock, shares 20,716,878 20,538,327
Preferred stock, par value $ 0.01 $ 0.01
Preferred stock, shares authorized 10,000,000 10,000,000
Preferred stock, shares issued 0 0
Preferred stock, shares outstanding 0 0