Summary of Significant Accounting Policies (Schedule of Stock by Class) (Details) - shares		12 Months Ended
	Oct. 21, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Class A  Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance (in shares)		29,975,000	44,078,000	44,749,000
Share repurchases	(10,800,000)	0	(14,785,000)	(1,302,000)
Net share issuance under employee stock plans		917,000	682,000	631,000
Ending Balance (in shares)		30,892,000	29,975,000	44,078,000
Class B  Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance (in shares)		11,484,000	11,484,000	11,484,000
Share repurchases			0	0
Net share issuance under employee stock plans		0	0	0
Ending Balance (in shares)		11,484,000	11,484,000	11,484,000