Consolidated Balance Sheets (Unaudited) (Parentheticals) (USD $) In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Allowance for doubtful accounts (in Dollars)	$ 266	$ 261
Property and equipment, accumulated depreciation (in Dollars)	$ 102,465	$ 99,115
Preferred stock, par value (in Dollars per share)	$ 0	$ 0
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)	$ 0	$ 0
Common stock, shares authorized	100,000	100,000
Common stock, shares issued	22,365	22,195
Common stock, shares outstanding	22,365	22,195
Common Class B [Member]
Common stock, par value (in Dollars per share)	$ 0	$ 0
Common stock, shares authorized	25,000	25,000
Common stock, shares issued	3,612	3,762
Common stock, shares outstanding	3,612	3,762