CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities
Net loss	$ (12,682,982)	$ (5,334,067)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	44,149	16,870
Stock-based compensation expense	1,620,831	813,678
Change in fair value of derivative liabilities	(289,666)	(285,021)
Change in fair value of contingent consideration	1,048,000
Non-cash interest expense	699,814
Debt exchange expense	818,541
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(312,239)	(1,100,510)
Accounts payable, accrued expenses and other liabilities	1,817,838	(144,341)
Net cash used in operating activities	(7,235,714)	(6,033,391)
Cash flows from investing activities
Purchase of property and equipment	(34,488)	(359,016)
Purchase of short-term investments	(8,918,946)	(27,318,092)
Purchase of long-term investments		(804,044)
Sales and maturities of short-term investments	20,861,548
Net cash provided by (used in) investing activities	11,908,114	(28,481,152)
Cash flows from financing activities
Proceeds from exercise of stock options and warrants	28,506	95,745
Retirement of convertible notes payable	(825,001)
Net cash provided by (used in) financing activities	(796,495)	95,745
Effect of exchange rate changes on cash and cash equivalents	21,516
Net increase (decrease) in cash and cash equivalents	3,897,421	(34,418,798)
Cash and cash equivalents - beginning of period	13,073,137	55,135,508
Cash and cash equivalents - end of period	16,970,558	20,716,710
Noncash investing and financing activities
Conversion of convertible notes to common stock	$ 2,080,292