SELECTED QUARTERLY FINANCIAL DATA (UNADUITED) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Schedule of selected quarterly financial data (unaudited)

The following tables set forth certain unaudited quarterly financial data for each of the eight quarters beginning with the quarter ended March 31, 2017 through the quarter ended December 31, 2018 (in thousands). This quarterly financial data is unaudited, but has been prepared on the same basis as the annual financial statements and, in the opinion of management, reflects all adjustments, consisting only of normal recurring adjustments necessary for a fair representation of the information for the periods presented. Operating results for any quarter are not necessarily indicative of results for any future period.

	2018 Quarter Ended
(in thousands)	March 31,		June 30,			September 30,		December 31,
Product sales	$	44,354	$	26,838		$	29,435	$	29,339
Total revenues	128,404		63,274			77,493		42,599
Gross margin on product sales	32,310		24,085			26,460		28,635
(Loss) income from operations	51,338		(4,225		)	9,628		(13,082		)
Net income (loss)	33,824		(21,048		)	48,270		(24,138		)
Basic net loss per share	$	0.53	$	(0.33	)	$	0.76	$	(0.38	)
Diluted net loss per share	$	0.48	$	(0.33	)	$	0.65	$	(0.38	)

	2017 Quarter Ended
(in thousands)	March 31,			June 30,			September 30,			December 31,
Product sales	$	90,285		$	100,232		$	95,204		$	94,159
Total revenues	90,447			100,457			95,413			94,407
Gross margin on product sales	72,511			80,507			77,808			76,455
Loss from operations	(6,665		)	(4,068		)	1,238			(32,685		)
Net loss	(26,741		)	(26,659		)	(15,992		)	(33,104		)
Basic net loss per share	$	(0.43	)	$	(0.43	)	$	(0.25	)	$	(0.52	)
Diluted net loss per share	$	(0.43	)	$	(0.43	)	$	(0.25	)	$	(0.52	)