CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2016		34,336,147
Beginning balance at Dec. 31, 2016	$ 934,389	$ 343	$ 1,238,031	$ (3,838)	$ (300,147)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Settlement of warrants	323		323
Equity component of the 2022 Convertible Notes, net of issuance costs and taxes	43,236		43,236
Equity component of debt repurchase	(27,988)		(27,988)
Shares issued in connection with Endoceutics License Agreement (in shares)		600,000
Shares issued in connection with Endoceutics License Agreement	13,500	$ 6	13,494
Repurchase and retirement of common stock pursuant to the 2016 Share Repurchase Program (in shares)		(1,366,266)
Repurchase and retirement of common stock pursuant to the 2016 Share Repurchase Program	(19,467)	$ (14)	(19,453)
Issuance of common stock under employee stock purchase plan (in shares)		120,580
Issuance of common stock under employee stock purchase plan	1,594	$ 1	1,593
Net shares issued in connection with the exercise of stock options and vesting of restricted stock units, net of withholdings (in shares)		392,651
Net shares issued in connection with the exercise of stock options and vesting of restricted stock units, net of withholdings	(1,267)	$ 5	(1,272)
Non-cash equity based compensation	23,664		23,664
Unrealized gains (losses) on securities, net of tax	(70)			(70)
Net loss	(199,228)				(199,228)
Ending balance (in shares) at Dec. 31, 2017		34,083,112
Ending balance at Dec. 31, 2017	$ 790,244	$ 341	1,271,628	(3,908)	(477,817)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase and retirement of common stock pursuant to the 2016 Share Repurchase Program (in shares)	0
Issuance of common stock under employee stock purchase plan (in shares)		59,872
Issuance of common stock under employee stock purchase plan	$ 918	$ 1	917
Net shares issued in connection with the exercise of stock options and vesting of restricted stock units, net of withholdings (in shares)		463,776
Net shares issued in connection with the exercise of stock options and vesting of restricted stock units, net of withholdings	279	$ 4	275
Non-cash equity based compensation	19,916		19,916
Unrealized gains (losses) on securities, net of tax	(77)			(77)
Net loss	$ (65,761)				(65,761)
Ending balance (in shares) at Dec. 31, 2018	34,606,760	34,606,760
Ending balance at Dec. 31, 2018	$ 746,655	$ 346	1,292,736	(3,985)	(542,442)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase and retirement of common stock pursuant to the 2016 Share Repurchase Program (in shares)	(1,074,800)
Repurchase and retirement of common stock pursuant to the 2016 Share Repurchase Program	$ (13,700)
Issuance of common stock under employee stock purchase plan (in shares)		185,937
Issuance of common stock under employee stock purchase plan	1,506	$ 1	1,505
Net shares issued in connection with the exercise of stock options and vesting of restricted stock units, net of withholdings (in shares)		281,184
Net shares issued in connection with the exercise of stock options and vesting of restricted stock units, net of withholdings	(1,800)	$ 3	(1,803)
Repurchase of common stock pursuant to the share repurchase program (in shares)		(1,074,800)
Repurchase of common stock pursuant to the share repurchase program	(13,730)	$ (11)	(13,719)
Non-cash equity based compensation	19,198		19,198
Unrealized gains (losses) on securities, net of tax	746			746
Net loss	$ (466,456)				(466,456)
Ending balance (in shares) at Dec. 31, 2019	33,999,081	33,999,081
Ending balance at Dec. 31, 2019	$ 286,119	$ 339	$ 1,297,917	$ (3,239)	$ (1,008,898)