Consolidated Balance Sheets (Parentheticals) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Allowance for doubtful accounts	$ 33,259	$ 25,052
Preferred stock par value	$ 0.0001	$ 0.0001
Preferred stock authorized	7,500,000	7,500,000
Preferred stock issued	0	0
Preferred stock outstanding	0	0
Common Class A [Member]
Common stock par value	$ 0.0001	$ 0.0001
Common stock authorized	80,000,000	80,000,000
Common stock issued	23,020,215	22,677,300
Common stock outstanding	23,020,215	22,677,300
Common Class B [Member]
Common stock par value	$ 0.0001	$ 0.0001
Common stock authorized	20,000,000	20,000,000
Common stock issued	5,164,765	5,175,343
Common stock outstanding	5,164,765	5,175,343