Consolidated Balance Sheets (Unaudited) (Parentheticals) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Allowance for doubtful accounts (in Dollars)	$ 153	$ 336
Accumulated depreciation (in Dollars)	$ 104,105	$ 97,883
Preferred stock, par value (in Dollars per share) (in Dollars per share)
Preferred stock, shares authorized	15,000	15,000
Preferred stock, shares outstanding	0	0
Common Class A [Member]
Common stock, par value (in Dollars per share)
Common stock, shares authorized	100,000	100,000
Common stock, shares issued	23,310	22,916
Common stock, shares outstanding	23,310	22,916
Common Class B [Member]
Common stock, par value (in Dollars per share)
Common stock, shares authorized	25,000	25,000
Common stock, shares issued	2,562	2,762
Common stock, shares outstanding	2,562	2,762