Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data	Jun. 30, 2011	Dec. 31, 2010
Current assets:
Allowance for doubtful accounts receivable	$ 3,335	$ 3,853
Shareholders' equity:
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	125,000,000	125,000,000
Series A: Common Stock
Shareholders' equity:
Common stock, shares issued	19,124,108	18,896,876
Series B: Common Stock
Shareholders' equity:
Common stock, shares issued	2,391,503	2,392,074