Significant Accounting Policies (Stock-based Compensation and Other) (Details) - Class A Common Stock - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Executives | Share-based Payment Arrangement [Member]
Schedule of Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued during the year under the Company's stock compensation plans (shares)	79,380	85,567
Class A common stock available for issuance under the plan (shares)	335,053
Compensation expense related to share awards	$ 2,000,000.0	$ 4,100,000
Compensation expense related to share awards, net of tax	1,600,000	3,300,000
Chairman | Restricted stock
Schedule of Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of directors, annual retainer paid in restricted shares	150,000	150,000
Annual non-employee directors retainer amount	$ 250,000	250,000
Non-employee directors | Share-based Payment Arrangement [Member]
Schedule of Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Class A common stock available for issuance under the plan (shares)	33,821
Compensation expense related to share awards	$ 1,000,000.0	1,100,000
Compensation expense related to share awards, net of tax	$ 800,000	$ 900,000
Non-employee directors | Restricted stock
Schedule of Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued during the year under the Company's stock compensation plans (shares)	42,744	22,258
Amount of directors, annual retainer paid in restricted shares	$ 100,000	$ 95,000
Annual non-employee directors retainer amount	$ 162,000	$ 155,000
Non-employee directors | Voluntary shares
Schedule of Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued during the year under the Company's stock compensation plans (shares)	745	432
Percentage of annual retainer that may be received in shares of Class A stock (percent)	100.00%
Participant's retirement date | Executives | Share-based Payment Arrangement [Member]
Schedule of Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration of restrictions on stock assignment, pledges or transfers	3 years
Participants retirement from board of directors | Non-employee directors | Share-based Payment Arrangement [Member]
Schedule of Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration of restrictions on stock assignment, pledges or transfers	5 years
Minimum age of director upon retirement from board | Non-employee directors | Share-based Payment Arrangement [Member]
Schedule of Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration of restrictions on stock assignment, pledges or transfers	70 years
Award date | Executives | Share-based Payment Arrangement [Member]
Schedule of Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration of restrictions on stock assignment, pledges or transfers	5 years
Award date | Non-employee directors | Share-based Payment Arrangement [Member]
Schedule of Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration of restrictions on stock assignment, pledges or transfers	10 years
Minimum | Award date | Executives | Share-based Payment Arrangement [Member]
Schedule of Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration of restrictions on stock assignment, pledges or transfers	3 years
Maximum | Award date | Executives | Share-based Payment Arrangement [Member]
Schedule of Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration of restrictions on stock assignment, pledges or transfers	10 years