Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets
Accounts receivable allowance for doubtful accounts	$ 555	$ 541
Stockholders' equity:
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value per share	$ 0.001	$ 0.001
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	63,190,000	59,009,000
Common stock, shares outstanding	62,908,000	58,272,000
Treasury stock, shares	4,181,000	4,181,000