Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net loss	$ (20,372,676)	$ (10,590,106)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation and amortization	14,620	21,767
Forgiveness of related party receivable	0	3,815
Stock-based compensation expense	1,892,835	979,151
Settlement for termination of certain rights in stock purchase agreement	0	913,446
Changes in operating assets and liabilities:
Prepaid and other current assets	540,118	(679,096)
Accounts payable	(449,562)	668,811
Accrued expenses	1,070,502	148,804
Income taxes payable	0	(55,048)
Cash used in operating activities	(17,304,163)	(8,588,456)
Cash flows from investing activities:
Refund of long-term rental deposit	21,247	0
Purchases of property and equipment	(59,608)	(1,206)
Cash used in investing activities	(38,361)	(1,206)
Cash flows from financing activities:
Proceeds from stock option exercises	16,064	10,575
Net proceeds from common stock offerings	0	48,518,771
Payment of accrued common stock offering costs	(271,183)	0
Purchase of restricted stock from employees	0	(53,100)
Cash provided by financing activities	(255,119)	48,476,246
Net decrease in cash and cash equivalents	(17,597,643)	39,886,584
Cash and cash equivalents at beginning of period	45,263,698	5,377,114
Cash and cash equivalents at end of period	27,666,055	45,263,698
Supplemental disclosure of non-cash financing activities:
Stock received as consideration for stock option exercises and recognized as treasury stock	40,712	0
Common Stock [Member]
Cash flows from operating activities:
Net loss	0	0
Supplemental disclosure of non-cash financing activities:
Accrued common stock offering costs	$ 0	$ 271,183