CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($)	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss)	Retained Earnings [Member]	Total
Balance at beginning of period at Dec. 31, 2013	$ 36,156	$ 262,060,590	$ 56,691	$ (173,924,716)	$ 88,228,721
Balances (in shares) at Dec. 31, 2013	36,155,509
Exercise of stock options	$ 400	1,290,486	0	0	$ 1,290,886
Exercise of stock options (in shares)	399,654				399,654
Stock-based compensation	$ 1	8,021,446			$ 8,021,447
Stock-based compensation (in shares)	1,279
Employee stock purchase plan	$ 53	299,176	0	0	299,229
Issuance of common stock in connection with secondary offering	$ 5,175	101,899,802			101,904,977
Issuance of common stock in connection with secondary offering (in shares)	5,175,000
Number of shares purchased under ESPP	53,250
Net income (loss)	$ 0	0	0	5,459,477	5,459,477
Unrealized loss on foreign currency translation	0	0	(38,776)	0	(38,776)
Unrealized loss on securities	0	0	(161,843)	0	(161,843)
Balance at end of period at Dec. 31, 2014	$ 41,785	373,571,500	(143,928)	(168,465,239)	205,004,118
Balances (in shares) at Dec. 31, 2014	41,784,692
Exercise of stock options	$ 146	379,144	0	0	$ 379,290
Exercise of stock options (in shares)	146,046				146,046
Stock-based compensation	$ 29	6,862,917	0	0	$ 6,862,946
Stock-based compensation (in shares)	29,190
Employee stock purchase plan	$ 75	304,928	0	0	305,003
Number of shares purchased under ESPP	74,805
Net income (loss)	$ 0	0	0	(41,269,749)	(41,269,749)
Unrealized loss on foreign currency translation	0	0	50,592	0	50,592
Unrealized loss on securities	0	0	13,937	0	13,937
Balance at end of period at Dec. 31, 2015	$ 42,035	381,118,489	(79,399)	(209,734,988)	171,346,137
Balances (in shares) at Dec. 31, 2015	42,034,733
Exercise of stock options	$ 130	260,952			$ 261,082
Exercise of stock options (in shares)	129,638				129,638
Stock-based compensation	$ 127	9,157,528			$ 9,157,655
Stock-based compensation (in shares)	126,580
Employee stock purchase plan	$ 86	231,773			231,859
Number of shares purchased under ESPP	86,571
Net income (loss)				(43,887,573)	(43,887,573)
Unrealized loss on securities	$ 0	0	38,203	0	38,203
Balance at end of period at Dec. 31, 2016	$ 42,378	$ 390,768,742	$ (41,196)	$ (253,622,561)	$ 137,147,363
Balances (in shares) at Dec. 31, 2016	42,377,522