CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Accounts receivable, allowance	$ 12,121	$ 10,771
Treasury stock - Common stock, Shares	68,110	66,725
Common Stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, Authorized	1,600,000	1,600,000
Common stock, Shares issued	190,657	189,255
Common stock, Shares outstanding	122,547	122,530
Class B Common Stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, Authorized	400,000	400,000
Common stock, Shares issued	12,800	12,800
Common stock, Shares outstanding	12,800	12,800