Condensed Consolidated Balance Sheets (Parentheticals) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Allowance for doubtful accounts	$ 5,138,000	$ 4,143,000
Unamortized debt discount, current	0	0
Deferred Costs, Current	449,000	136,000
Unamortized debt discount, noncurrent	0	0
Deferred Costs, Noncurrent	$ 1,748,000	$ 298,000
Stockholders' Equity Note [Abstract]
Common stock, shares issued	31,458,976	31,476,428
Common stock, shares outstanding	31,458,976	31,476,428
Treasury stock, shares	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (per share)	$ 0.10	$ 0.10
Common stock, shares authorized	120,000,000	120,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares authorized	500,000	500,000
Preferred stock, par value (per share)	$ 0.10	$ 0.10