Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net earnings	$ 57,284	$ 91,221	$ 13,944
Adjustments to reconcile net earnings to net cash provided by operating activities:
Loss on extinguishment of debt	295	671	2,338
Change in fair value of derivative liability	(76)	(448)	(193)
Depreciation and amortization	8,132	2,399	921
Amortization of deferred financing costs and debt discount	50	278	687
Amortization of premium/discount on marketable securities	(563)	242	61
Non-cash interest expense on non-recourse liability related to sale of future royalties	1,434	4,548	3,541
Non-cash royalty revenue	(5,283)	(4,686)	(3,038)
Share-based compensation expense	8,433	5,926	4,090
Deferred income tax provision	21,224	(41,787)
Changes in operating assets and liabilities:
Accounts receivable	(24,059)	(15,619)	(8,638)
Inventories	497	(4,214)	854
Prepaid expenses and other current assets	(3,566)	2,306	(1,582)
Accounts payable	(620)	3,470	2,061
Accrued sales deductions	26,400	15,149	18,333
Accrued expenses	2,888	7,539	507
Income taxes payable	15,931	7
Deferred licensing revenue	(274)	144	149
Other non-current liabilities	6,513	(334)	489
Net cash provided by operating activities	114,640	66,812	34,524
Cash flows from investing activities
Purchases of marketable securities	(101,889)	(47,364)	(63,859)
Sales and maturities of marketable securities	28,657	31,824	37,581
Purchases of property, plant and equipment	(2,029)	(1,603)	(2,104)
Deferred legal fees	(11,154)	(18,821)	(10,907)
Net cash used in investing activities	(86,415)	(35,964)	(39,289)
Cash flows from financing activities
Proceeds from issuance of common stock	5,681	2,052	1,867
Net cash provided by financing activities	5,681	2,052	1,867
Net change in cash and cash equivalents	33,906	32,900	(2,898)
Cash and cash equivalents at beginning of year	66,398	33,498	36,396
Cash and cash equivalents at end of year	100,304	66,398	33,498
Supplemental cash flow information:
Cash paid for interest	134	493	825
Income taxes paid	1,588
Noncash financial activity:
Conversion of convertible notes and interest make-whole	4,548	4,162	27,089
Exercise of warrants			652
Deferred legal fees included in accounts payable and accrued expenses	521	$ 5,122	$ 9,789
Unsettled purchase of marketable securities included in accrued expenses	$ 1,004