Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating activities:
Net loss	$ (51,579,000)	$ (63,012,000)
Adjustments to reconcile net loss to net cash used for operating activities:
Stock-based compensation expense	11,974,000	17,902,000
Depreciation and amortization	621,000	467,000
Amortization of debt discount	310,000	247,000
Realized gain on available-for-sale securities	0	(8,000)
Accretion of discount on short-term investments	(117,000)	(1,357,000)
Impairment of property and equipment	27,000	27,000
Loss on disposal of property and equipment		52,000
Change in operating assets and liabilities:
Accounts receivable	5,068,000	(9,355,000)
Prepaid expenses and other assets	10,803,000	(346,000)
Inventory	(9,881,000)	7,611,000
Accounts payable	8,804,000	(6,052,000)
Accrued clinical and manufacturing liabilities	707,000	(868,000)
Accrued payroll and employee liabilities	(6,478,000)	(6,757,000)
Other accrued liabilities	(3,194,000)	12,425,000
Net cash used for operating activities	(32,935,000)	(49,024,000)
Investing activities:
Purchases of short-term investments	(28,922,000)	(127,763,000)
Maturities and sales of short-term investments	95,675,000	164,009,000
Purchases of property and equipment	(2,938,000)	(2,136,000)
Net cash provided by investing activities	63,815,000	34,110,000
Financing activities:
Proceeds from stock option exercises	504,000	6,539,000
Proceeds from warrant exercises	3,000
Net cash provided by financing activities	507,000	6,539,000
Net increase (decrease) in cash and cash equivalents	31,387,000	(8,375,000)
Cash and cash equivalents at beginning of year	71,898,000	31,836,000
Cash and cash equivalents at end of period	$ 103,285,000	$ 23,461,000