Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Class A
Common Stock, par value	$ 0.01	$ 0.01
Common Stock, shares authorized	12,000,000	12,000,000
Common Stock, shares issued	6,577,100	6,577,100
Common Stock, shares outstanding	6,577,100	6,577,100
Class B
Common Stock, par value	$ 0.01	$ 0.01
Common Stock, shares authorized	150,000,000	150,000,000
Common Stock, shares issued	77,805,530	79,449,349
Common Stock, shares outstanding	77,805,530	79,449,349
Class C
Common Stock, par value	$ 0.01	$ 0.01
Common Stock, shares authorized	1,200,000	1,200,000
Common Stock, shares issued	661,688	661,688
Common Stock, shares outstanding	661,688	661,688
Class D
Common Stock, par value	$ 0.01	$ 0.01
Common Stock, shares authorized	5,000,000	5,000,000
Common Stock, shares issued	18,251	18,491
Common Stock, shares outstanding	18,251	18,491