Note 20 - Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2014

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information [Table Text Block]

Year 2014	Quarter ended December 31,		Quarter ended September 30,		Quarter ended June 30,		Quarter ended March 31,
Product revenue	$	17,880,125	$	21,975,312	$	21,267,156	$	14,351,405
Total revenue		23,254,469		22,055,423		26,274,660		34,010,287
Cost of product revenue		5,511,586		5,724,800		5,332,913		4,361,019
Gross profit on product revenue		12,368,539		16,250,512		15,934,243		9,990,386
Net income	$	7,816,076	$	6,170,800	$	9,302,350	$	15,030,253
Per common share information:
Basic net income per share	$	0.53	$	0.42	$	0.63	$	1.04
Basic common shares outstanding		14,800,813		14,758,781		14,687,747		14,461,367
Diluted net income per share	$	0.51	$	0.40	$	0.60	$	0.97
Diluted common shares outstanding		15,277,583		15,434,875		15,492,732		15,499,447

Year 2013	Quarter ended December 31,		Quarter ended September 30,		Quarter ended June 30,		Quarter ended March 31,
Product revenue	$	20,188,488	$	17,023,346	$	20,067,407	$	14,494,489
Total revenue		21,251,328		17,754,438		20,828,377		15,247,011
Cost of product revenue		6,235,334		5,377,568		6,311,332		4,841,170
Gross profit on product revenue		13,953,154		11,645,778		13,756,075		9,653,319
Net income	$	6,654,369	$	4,957,258	$	5,894,892	$	3,068,002
Per common share information:
Basic net income per share	$	0.47	$	0.36	$	0.44	$	0.23
Basic common shares outstanding		14,272,606		13,682,449		13,510,573		13,406,952
Diluted net income per share	$	0.44	$	0.33	$	0.40	$	0.21
Diluted common shares outstanding		15,084,738		14,958,965		14,578,927		14,357,110