Basic and Diluted Net Income (Loss) Per Share (Tables)

3 Months Ended

Mar. 31, 2018

Earnings Per Share [Abstract]

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

	Three Months Ended
	March 31,
	2018	2017
Stock options	5,411	3,827
Restricted stock units	306	541
Performance-based restricted stock units (B)	335	1,049
Warrants	6,067	—
Total equity award shares excluded	12,119	5,417

(B) Performance-based restricted stock units are presented based on attainment of 100% of the performance goals being met.

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

A reconciliation of the numerator and the denominator used to calculate basic and diluted net loss per share is as follows (in thousands, except per share amounts):

	Three Months Ended
	March 31,
	2018			2017
Numerator
Net loss	$	(6,445	)	$	(10,008	)
Denominator — Basic
Weighted average shares used to calculate net loss per share, basic	39,355			38,715
Denominator — Diluted
Weighted average shares used to calculate net loss per share, basic	39,355			38,715
Effect of dilutive restricted stock units (A)	—			—
Effect of dilutive stock options (A)	—			—
Weighted average shares used to calculate net loss per share, diluted	39,355			38,715
Net loss per share
Basic	$	(0.16	)	$	(0.26	)
Diluted	$	(0.16	)	$	(0.26	)