Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Accounts receivable allowance	$ 2,916	$ 3,055
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000	5,000
Preferred stock, shares issued
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	450,000	450,000
Series A Common Stock
Common stock, par value	$ 0.01
Common stock, shares issued	95,036	93,672
Common stock shares outstanding	95,036	93,672
Series B Common Stock
Common stock, par value	$ 0.01
Common stock, shares issued	8,282	10,115
Common stock shares outstanding	8,282	10,115