CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Current Assets:
Accounts receivable, allowances	$ 2,903	$ 1,414
LIABILITIES AND STOCKHOLDERS' EQUITY
Preferred Stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred Stock, shares authorized ( in shares)	25,000,000	25,000,000
Preferred Stock, shares issued ( in shares)	0	0
Preferred Stock, shares outstanding ( in shares)	0	0
Treasury stock, shares (in shares)	4,931,872	4,882,672
Common Class A [Member]
LIABILITIES AND STOCKHOLDERS' EQUITY
Common Stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, shares authorized (in shares)	160,000,000	160,000,000
Common Stock, shares issued (in shares)	24,980,958	24,816,738
Common Stock, shares outstanding (in shares)	20,049,086	19,934,066
Common Class B [Member]
LIABILITIES AND STOCKHOLDERS' EQUITY
Common Stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, shares authorized (in shares)	30,000,000	30,000,000
Common Stock, shares issued (in shares)	2,919,790	3,040,620
Common Stock, shares outstanding (in shares)	2,919,790	3,040,620