CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)
In Thousands, except Share data, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Accounts receivable, allowance for doubtful accounts (in dollars) $ 1,436 $ 1,409
Accumulated depreciation (in dollars) $ 97,271 $ 95,083
Preferred stock, shares issued 0 0
Shares to be issued, shares 0 0
Common Class A    
Common stock, shares issued 49,846,285 49,680,109
Common stock, shares outstanding 49,846,285 49,680,109
Common Class B    
Common stock, shares issued 3,755 3,755
Common stock, shares outstanding 3,755 3,755