Summary of Significant Accounting Policies (Details Textual)										1 Months Ended			12 Months Ended
	Sep. 14, 2018 USD ($) $ / shares	May 15, 2018 USD ($) $ / shares	Dec. 07, 2017 USD ($) $ / shares	Sep. 13, 2017 USD ($) $ / shares	May 03, 2017 USD ($) $ / shares	Mar. 03, 2017 USD ($) $ / shares	Nov. 21, 2016 USD ($) $ / shares	Jun. 01, 2016 USD ($) $ / shares	Mar. 02, 2016 USD ($) $ / shares	Nov. 28, 2018 USD ($) $ / shares	Feb. 28, 2018 USD ($) $ / shares	Aug. 30, 2016 USD ($) $ / shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares
Summary Of Significant Accounting Policies [Line Items]
Concentration Risk, Market Risk													41.00%	41.00%	43.00%
Interest expense related to the amortization of debt issuance costs													$ 51,000	$ 53,000	$ 53,000
Write-off of debt issuance costs															$ 53,000
Net book value of deferred costs													$ 207,000	$ 138,000
Treasury Stock, Shares, Acquired | shares													53,713	37,141	18,612
Treasury Stock Acquired, Average Cost Per Share | $ / shares													$ 37.24	$ 47.72	$ 40.06
Special cash dividend declared on Classes A and B Common Stock | $ / shares	$ 0.30	$ 0.30	$ 0.30	$ 0.30	$ 0.30	$ 0.30	$ 0.30	$ 0.25	$ 0.25	$ 0.30	$ 0.30	$ 0.30	$ 1.45	$ 2.00	$ 1.30
Dividend paid	$ 1,800,000	$ 1,800,000	$ 6,500,000	$ 1,800,000	$ 1,800,000	$ 1,800,000	$ 2,900,000	$ 1,500,000	$ 1,500,000	$ 3,300,000	$ 1,800,000	$ 1,800,000
Number Of Broadcast Licenses													112
Number Of Market Serving													27
Dividends Payable, Amount Per Share | $ / shares			$ 0.80				$ 0.20			$ 0.25
Debt Issuance Costs, Net													$ 120,000
Accounting Standards Update 2016-02 [Member]
Summary Of Significant Accounting Policies [Line Items]
Operating Lease, Liability													7,000,000
Continuing Operations [Member]
Summary Of Significant Accounting Policies [Line Items]
Depreciation expense													5,692,000	$ 5,391,000	$ 5,234,000
Advertising and promotion costs													2,438,000	2,441,000	2,633,000
Discontinued Operations [Member]
Summary Of Significant Accounting Policies [Line Items]
Depreciation expense													0	445,000	1,387,000
Advertising and promotion costs													0	$ 240,000	$ 341,000
Class A Common Stock [Member]
Summary Of Significant Accounting Policies [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount													20,400,000
Minimum [Member] | Class A Common Stock [Member]
Summary Of Significant Accounting Policies [Line Items]
Stock Repurchase Program, Authorized Amount													60,000,000
Maximum [Member] | Class A Common Stock [Member]
Summary Of Significant Accounting Policies [Line Items]
Stock Repurchase Program, Authorized Amount													$ 75,800,000