Condensed Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Other Accumulated Comprehensive Gain (Loss)	Accumulated Deficit
Beginning Balance (in shares) at Dec. 31, 2018		0	36,975,203
Beginning Balance at Dec. 31, 2018		$ 0	$ 37	$ 830,368	$ (8)	$ (684,775)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock awards and performance stock awards, net of cancellation (in shares)			391,023
Issuance of common stock in connection with offerings (in shares)			6,764,705
Issuance of common stock in connection with offerings			$ 7	107,572
Issuance of common stock upon exercise of stock options and warrants (in shares)			8,240
Issuance of common stock relating to employee stock purchase plan (in shares)			35,166
Net settlement of restricted stock awards for employee taxes (in shares)			(68,863)
Issuance of common stock upon exercise of stock options and warrants				93
Issuance of common stock relating to employee stock purchase plan				387
Stock-based compensation				8,579
Net settlement of restricted stock awards for employee taxes				(1,148)
Unrealized gain (loss) and adjustment on securities included in net loss	$ 124				124
Net loss	$ (72,694)					(72,694)
Ending Balance (in shares) at Jun. 30, 2019	44,105,474	0	44,105,474
Ending Balance at Jun. 30, 2019	$ 188,542	$ 0	$ 44	945,851	116	(757,469)
Beginning Balance (in shares) at Mar. 31, 2019		0	44,004,658
Beginning Balance at Mar. 31, 2019		$ 0	$ 44	941,068	70	(720,079)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock awards and performance stock awards, net of cancellation (in shares)			67,997
Issuance of common stock upon exercise of stock options and warrants (in shares)			5,416
Issuance of common stock relating to employee stock purchase plan (in shares)			35,166
Net settlement of restricted stock awards for employee taxes (in shares)			(7,763)
Issuance of common stock upon exercise of stock options and warrants				75
Issuance of common stock relating to employee stock purchase plan				387
Stock-based compensation				4,420
Net settlement of restricted stock awards for employee taxes				(99)
Unrealized gain (loss) and adjustment on securities included in net loss	46				46
Net loss	$ (37,390)					(37,390)
Ending Balance (in shares) at Jun. 30, 2019	44,105,474	0	44,105,474
Ending Balance at Jun. 30, 2019	$ 188,542	$ 0	$ 44	945,851	116	(757,469)
Beginning Balance (in shares) at Dec. 31, 2019	52,374,735	0	52,374,735
Beginning Balance at Dec. 31, 2019	$ 225,490	$ 0	$ 52	1,069,639	3	(844,204)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with the Teoxane Agreement (in shares)			2,500,000
Issuance of common stock in connection with the Teoxane Agreement			$ 3	43,397
Issuance of restricted stock awards and performance stock awards, net of cancellation (in shares)			1,417,853
Issuance of restricted stock awards and performance stock awards, net of cancellation			$ 1	(1)
Issuance of common stock in connection with offerings (in shares)			975,000
Issuance of common stock in connection with offerings			$ 1	15,536
Issuance of common stock upon exercise of stock options and warrants (in shares)			76,794
Issuance of common stock relating to employee stock purchase plan (in shares)			48,661
Net settlement of restricted stock awards for employee taxes (in shares)			(79,487)
Issuance of common stock upon exercise of stock options and warrants				999
Issuance of common stock relating to employee stock purchase plan				671
Equity component of convertible senior notes, net of transaction costs	108,510
Stock-based compensation				13,897
Capped call transactions				(28,865)
Net settlement of restricted stock awards for employee taxes				(1,512)
Unrealized gain (loss) and adjustment on securities included in net loss	114				114
Net loss	$ (122,523)					(122,523)
Ending Balance (in shares) at Jun. 30, 2020	57,313,556	0	57,313,556
Ending Balance at Jun. 30, 2020	$ 255,718	$ 0	$ 57	1,222,271	117	(966,727)
Beginning Balance (in shares) at Mar. 31, 2020		0	57,026,154
Beginning Balance at Mar. 31, 2020		$ 0	$ 57	1,213,931	524	(906,137)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock awards and performance stock awards, net of cancellation (in shares)			220,799
Issuance of common stock upon exercise of stock options and warrants (in shares)			24,442
Issuance of common stock relating to employee stock purchase plan (in shares)			48,661
Net settlement of restricted stock awards for employee taxes (in shares)			(6,500)
Issuance of common stock upon exercise of stock options and warrants				427
Issuance of common stock relating to employee stock purchase plan				671
Stock-based compensation				7,353
Net settlement of restricted stock awards for employee taxes				(111)
Unrealized gain (loss) and adjustment on securities included in net loss	(407)				(407)
Net loss	$ (60,590)					(60,590)
Ending Balance (in shares) at Jun. 30, 2020	57,313,556	0	57,313,556
Ending Balance at Jun. 30, 2020	$ 255,718	$ 0	$ 57	$ 1,222,271	$ 117	$ (966,727)