Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common stock	Additional paid-in capital	Accumulated other comprehensive income (loss)	Accumulated deficit
Beginning balance (in shares) at Dec. 31, 2016		42,526
Beginning balance at Dec. 31, 2016	$ 225,405	$ 106	$ 532,378	$ (8,401)	$ (298,678)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	(44,534)			8,799	(53,333)
Issuance of common stock upon exercise of stock options (in shares)		665
Issuance of common stock upon exercise of stock options	2,483	$ 2	2,481
Issuance of common stock under employee stock purchase plan (in shares)		349
Issuance of common stock under employee stock purchase plan	2,393	$ 1	2,392
Issuance of common stock for vested restricted stock units (in shares)		806
Issuance of common stock for vested restricted stock units	0	$ 2	(2)
Tax withholding related to vesting of restricted stock units (in shares)		(127)
Tax withholding related to vesting of restricted stock units	(998)		(998)
Stock-based compensation costs	9,702		9,702
Ending Balance (in shares) at Dec. 31, 2017		44,219
Ending balance at Dec. 31, 2017	194,451	$ 111	545,953	398	(352,011)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact of adoption of new accounting standard ASU 2016-16	(1,824)				(1,824)
Comprehensive income (loss)	(51,161)			(7,524)	(43,637)
Issuance of common stock upon exercise of stock options (in shares)		779
Issuance of common stock upon exercise of stock options	3,422	$ 2	3,420
Issuance of common stock under employee stock purchase plan (in shares)		404
Issuance of common stock under employee stock purchase plan	2,191	$ 1	2,190
Issuance of common stock for vested restricted stock units (in shares)		1,124
Issuance of common stock for vested restricted stock units	0	$ 2	(2)
Tax withholding related to vesting of restricted stock units (in shares)		(148)
Tax withholding related to vesting of restricted stock units	(954)		(954)
Stock-based compensation costs	14,115		14,115
Ending Balance (in shares) at Dec. 31, 2018		46,378
Ending balance at Dec. 31, 2018	160,240	$ 116	564,722	(7,126)	(397,472)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	(17,821)			(745)	(17,076)
Issuance of common stock in exchange for research and development services, net of issuance costs of $46 (in shares)		442
Issuance of common stock in exchange for research and development services, net of issuance costs of $46	2,454	$ 1	2,453
Issuance of common stock upon exercise of stock options (in shares)		486
Issuance of common stock upon exercise of stock options	1,893	$ 1	1,892
Issuance of common stock under employee stock purchase plan (in shares)		357
Issuance of common stock under employee stock purchase plan	1,953	$ 1	1,952
Issuance of common stock for vested restricted stock units (in shares)		1,018
Issuance of common stock for vested restricted stock units	0	$ 2	(2)
Tax withholding related to vesting of restricted stock units (in shares)		(155)
Tax withholding related to vesting of restricted stock units	(733)		(733)
Stock-based compensation costs	12,220		12,220
Ending Balance (in shares) at Dec. 31, 2019		48,526
Ending balance at Dec. 31, 2019	$ 160,206	$ 121	$ 582,504	$ (7,871)	$ (414,548)