Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees, net of expense reversals.

No definition available.

Accounting for Shared-based Payments - Stock Options (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Jun. 08, 2015	Jun. 07, 2015
Shared-based payments
Total stock-based compensation expense	$ 4,585	$ (69)	$ 8,494	$ 7,724
Research and development \| Employee
Shared-based payments
Total stock-based compensation expense	961	592	2,555	1,702
General and administrative \| Employee
Shared-based payments
Total stock-based compensation expense	3,624	$ (661)	$ 5,939	$ 6,022
2008 Equity Compensation Incentive Plan
Shared-based payments
Number of shares reserved under the plan (in shares)					30,000,000	15,000,000
Stock Options
Shared-based payments
Vesting period			3 years
Contractual term			10 years
Unrecognized compensation cost related to non-vested employee stock options, net of expected forfeitures	$ 18,800		$ 18,800
Weighted-average remaining vesting period over which unrecognized compensation cost is to be recognized			1 year 3 months 18 days
Number of stock options which vest upon a change of control (in shares)	2,159,500		2,159,500
Weighted-average assumptions used to estimate fair value of stock option awards using the Black-Scholes option valuation model
Risk-free interest rate, minimum			1.13%	1.46%
Risk-free interest rate, maximum			1.74%	2.02%
Dividend yield			0.00%	0.00%
Expected volatility			50.00%
Expected volatility, minimum				57.00%
Expected volatility, maximum				80.00%
Expected term			6 years	6 years