CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Earnings (Deficit)	Accumulated Other Comprehensive Loss
Balances (in shares) at Dec. 31, 2018		64,185
Balances at Dec. 31, 2018	$ 220,335	$ 6	$ 402,934	$ (182,600)	$ (5)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of options (in shares)		14
Issuance of common stock upon exercise of options	25		25
Issuance of common stock in conjunction with vesting of restricted stock units (in shares)		132
Stock-based compensation	2,702		2,702
Shares withheld for payment of employee's withholding tax liability	(216)		(216)
Net income (loss)	(14,301)			(14,301)
Balances (in shares) at Mar. 31, 2019		64,331
Balances at Mar. 31, 2019	208,545	$ 6	405,445	(196,901)	(5)
Balances (in shares) at Dec. 31, 2018		64,185
Balances at Dec. 31, 2018	220,335	$ 6	402,934	(182,600)	(5)
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(24,575)
Balances (in shares) at Sep. 30, 2019		80,680
Balances at Sep. 30, 2019	248,434	$ 8	455,601	(207,175)	0
Balances (in shares) at Mar. 31, 2019		64,331
Balances at Mar. 31, 2019	208,545	$ 6	405,445	(196,901)	(5)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under employee stock purchase plan (in shares)		64
Issuance of common stock under employee stock purchase plan	158		158
Issuance of common stock in conjunction with vesting of restricted stock units (in shares)		426
Stock-based compensation	2,634		2,634
Shares withheld for payment of employee's withholding tax liability	(293)		(293)
Net income (loss)	(13,605)			(13,605)
Balances (in shares) at Jun. 30, 2019		64,821
Balances at Jun. 30, 2019	197,439	$ 6	407,944	(210,506)	(5)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock in conjunction with vesting of restricted stock units (in shares)		42
Issuance of common stock in conjunction with the Convertible Note Exchange (in shares)		15,817
Issuance of common stock in conjunction with the Convertible Note Exchange	25,307	$ 2	25,305
Reacquisition of equity component of 2021 Notes and 2024 Notes	(4,796)		(4,796)
Equity component of issued 2024 Notes, net of tax	24,165		24,165
Stock-based compensation	3,004		3,004
Shares withheld for payment of employee's withholding tax liability	(19)		(19)
Net income (loss)	3,331			3,331
Unrealized loss on available-for-sale securities	5				5
Balances (in shares) at Sep. 30, 2019		80,680
Balances at Sep. 30, 2019	248,434	$ 8	455,601	(207,175)	$ 0
Balances (in shares) at Dec. 31, 2019		80,888
Balances at Dec. 31, 2019	57,958	$ 8	457,751	(399,801)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock in conjunction with vesting of restricted stock units (in shares)		434
Reacquisition of equity component of 2021 Notes and 2024 Notes	(16,814)		(16,814)
Stock-based compensation	1,934		1,934
Shares withheld for payment of employee's withholding tax liability	(271)		(271)
Net income (loss)	41,230			41,230
Balances (in shares) at Mar. 31, 2020		81,322
Balances at Mar. 31, 2020	84,037	$ 8	442,600	(358,571)
Balances (in shares) at Dec. 31, 2019		80,888
Balances at Dec. 31, 2019	57,958	$ 8	457,751	(399,801)
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(3,791)
Balances (in shares) at Sep. 30, 2020		107,174
Balances at Sep. 30, 2020	75,950	$ 12	479,530	(403,592)
Balances (in shares) at Mar. 31, 2020		81,322
Balances at Mar. 31, 2020	84,037	$ 8	442,600	(358,571)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under employee stock purchase plan (in shares)		76
Issuance of common stock under employee stock purchase plan	49		49
Issuance of common stock in conjunction with vesting of restricted stock units (in shares)		215
Issuance of common stock in conjunction with the Zyla Merger (in shares)		25,479
Issuance common stock, warrants, and stock options in conjunction with the Zyla Merger	22,931	$ 3	22,928
Issuance of warrants and stock options in conjunction with the Zyla Merger	11,626		11,626
Reacquisition of equity component of 2021 Notes and 2024 Notes	(2,718)		(2,718)
Stock-based compensation	3,593		3,593
Shares withheld for payment of employee's withholding tax liability	(41)		(41)
Net income (loss)	(34,499)			(34,499)
Balances (in shares) at Jun. 30, 2020		107,092
Balances at Jun. 30, 2020	84,978	$ 11	478,037	(393,070)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock in conjunction with vesting of restricted stock units (in shares)		82
Issuance of common stock in conjunction with vesting of restricted stock units	1	$ 1
Stock-based compensation	1,511		1,511
Shares withheld for payment of employee's withholding tax liability	(18)		(18)
Net income (loss)	(10,522)			(10,522)
Balances (in shares) at Sep. 30, 2020		107,174
Balances at Sep. 30, 2020	$ 75,950	$ 12	$ 479,530	$ (403,592)