CONDENSED CONSOLIDATEDSTATEMENT OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities:
Net loss	$ (32,940)	$ (21,149)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	1,147	729
Amortization of intangible assets	5	5
Amortization of investment discount	123	99
Equity-based compensation	3,921	4,185
(Increase) decrease in assets:
Accounts receivable	(92)	(65)
Prepaid expense and other	272	(675)
Other current assets	(1,220)	0
Increase (decrease) in liabilities:
Accounts payable	(394)	(129)
Accrued liabilities	1,175	657
Deferred revenue and income	(84)	(14)
Net cash used in operating activities	(28,087)	(16,357)
Cash flows from investing activities:
Purchases of equipment	(2,084)	(2,160)
Purchases of available-for-sale securities	(63,534)	(8,017)
Sales of available-for-sale securities	1,000	141
Maturity of available-for-sale securities	9,380	7,807
Net cash used in investing activities	(55,238)	(2,229)
Cash flows from financing activities:
Exercise of options	95	327
Common stock issuance costs	(814)	0
Payments on capital lease obligations	(13)	(73)
Recovery of related party short-swing profits	991	0
Net cash provided by financing activities	259	254
Decrease in cash and cash equivalents	(83,066)	(18,332)
Cash and cash equivalents, beginning of period	120,585	53,563
Cash and cash equivalents, end of period	$ 37,519	$ 35,231