CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 1,852	$ 2,011
Accumulated depreciation (in dollars)	$ 117,903	$ 118,119
Preferred stock, shares issued	0	0
Shares to be issued, shares	42,000	42,000
Common Class A [Member]
Common stock, shares issued	49,476,405	49,092,427
Common stock, shares outstanding	49,476,405	49,092,427
Common Class B [Member]
Common stock, shares issued	3,755	3,755
Common stock, shares outstanding	3,755	3,755