Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Computation of basic and diluted net loss per share [Abstract]
Net income	$ 3,321	$ 6,551	$ 6,493	$ 16,068
Denominator for basic earnings per share - weighted average shares (in shares)	105,991,990	106,511,294	105,927,890	106,178,136
Effect of dilutive securities: Stock options, restricted stock, and warrants outstanding (in shares)	6,369,189	8,044,742	6,265,811	7,931,984
Denominator for diluted earnings per share - weighted average shares adjusted for dilutive securities (in shares)	112,361,179	114,556,036	112,193,701	114,110,120
Income per common share - basic (in dollars per share)	$ 0.03	$ 0.06	$ 0.06	$ 0.15
Income per common share - diluted (in dollars per share)	$ 0.03	$ 0.06	$ 0.06	$ 0.14
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	6,369,189	8,044,742	6,265,811	7,931,984
Outstanding Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	5,704,112	7,320,155	5,767,469	7,366,426
Outstanding Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0	38,023	0	37,820
Restricted Stock Awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	665,077	686,564	498,342	527,738