Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Condensed Consolidated Balance Sheets [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 727	$ 571
Cumulative convertible preferred stock at accreted value, par value	$ 0.0001	$ 0.0001
Cumulative convertible preferred stock, shares authorized	100,000	100,000
Cumulative convertible preferred stock, shares issued	0	0
Cumulative convertible preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	80,000,000	80,000,000
Common stock, shares issued	52,819,006	51,957,652
Common stock, shares outstanding	49,310,965	49,153,495
Treasury stock, shares	1,377,889	1,358,299