Common Stock and Treasury Stock - Information Relating to the Number of Shares of Our Common Stock Issued (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2020 shares
Class A Common Stock
Common Stock [Line Items]
Balance, shares	6,771
Conversion of shares	16
Issuance of restricted stock	0
Forfeiture of restricted stock (in shares)	(2)
Balance, shares	6,785
Class B Common Stock
Common Stock [Line Items]
Balance, shares	954
Conversion of shares	(16)
Issuance of restricted stock	0
Forfeiture of restricted stock (in shares)	0
Balance, shares	938