Net Income (Loss) Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended												9 Months Ended	12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Numerator:
Net income (loss)	$ (76)	$ (8,295)	$ 19,787	$ (5,726)	$ (8,229)	$ 601	$ (520)	$ (2,254)	$ 14,205	$ (2,206)	$ (4,789)	$ (5,445)		$ 5,690	$ (10,402)	$ 1,765
Denominator for basic and diluted net income (loss) per share:
Weighted average common shares outstanding for basic														55,686,000	55,696,000	55,489,000
Dilutive potential common stock equivalents														1,375,000	0	548,000
Weighted average common shares outstanding for diluted														57,061,000	55,696,000	56,037,000
Basic net income (loss) per share	$ (0.001)	$ (0.15)	$ 0.36	$ (0.10)	$ (0.15)	$ 0.01	$ (0.01)	$ (0.04)	$ 0.26	$ (0.04)	$ (0.09)	$ (0.10)		$ 0.10	$ (0.19)	$ 0.03
Diluted net income (loss) per share	$ (0.001)	$ (0.15)	$ 0.35	$ (0.10)	$ (0.15)	$ 0.01	$ (0.01)	$ (0.04)	$ 0.25	$ (0.04)	$ (0.09)	$ (0.10)		$ 0.10	$ (0.19)	$ 0.03
Potentially dilutive securities excluded from computation of diluted not loss per share (Shares)													3,800,000	3,300,000	7,600,000