CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current Assets:
Accounts receivable, allowances	$ 4,016	$ 3,461
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
Common Stock, par value (in dollars per share)	$ 0.01	$ 0.01
Treasury stock, shares (in shares)	4,931,872	4,931,872
Class A Common Stock [Member]
LIABILITIES AND STOCKHOLDERS' EQUITY
Common Stock, shares authorized (in shares)	160,000,000	160,000,000
Common Stock, shares issued (in shares)	25,005,058	25,004,381
Common Stock, shares outstanding (in shares)	20,073,186	20,072,509
Class B Common Stock [Member]
LIABILITIES AND STOCKHOLDERS' EQUITY
Common Stock, shares authorized (in shares)	30,000,000	30,000,000
Common Stock, shares issued (in shares)	2,899,682	2,897,996
Common Stock, shares outstanding (in shares)	2,899,682	2,897,996