Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2011	Dec. 31, 2010
Class A Common [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	12,000,000	12,000,000
Common stock, shares issued	6,625,708	6,656,308
Common stock, shares outstanding	6,625,708	6,656,308
Class B Common [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	89,286,305	90,093,562
Common stock, shares outstanding	89,286,305	90,093,562
Class C Common [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,200,000	1,200,000
Common stock, shares issued	664,000	665,400
Common stock, shares outstanding	664,000	665,400
Class D Common [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	5,000,000	5,000,000
Common stock, shares issued	33,164	35,218
Common stock, shares outstanding	33,164	35,218