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Summary of Significant Accounting Policies (Narrative) (Details) |  |  |  |  |  |  |  |  | 1 Months Ended | 12 Months Ended |  |  |
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Mar. 04, 2020 USD ($) $ / shares | Dec. 11, 2019 USD ($) $ / shares | Sep. 12, 2019 USD ($) $ / shares | Jul. 05, 2019 USD ($) | May 30, 2019 $ / shares | Feb. 26, 2019 USD ($) $ / shares | Sep. 14, 2018 USD ($) $ / shares | May 15, 2018 USD ($) $ / shares | Nov. 28, 2018 USD ($) $ / shares | Feb. 28, 2018 USD ($) $ / shares | Dec. 31, 2020 USD ($) segment $ / shares shares | Dec. 31, 2019 USD ($) $ / shares shares | Dec. 31, 2018 USD ($) $ / shares shares | Dec. 31, 2020 USD ($) | Dec. 31, 2020 | Dec. 31, 2020 item | Mar. 31, 2013 USD ($) | Feb. 28, 2013 USD ($)
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number Of FM Radio Stations |  |  |  |  |  |  |  |  |  |  | 79 |  |  |  |  |  |  |
Number Of AM Radio Stations |  |  |  |  |  |  |  |  |  |  | 34 |  |  |  |  |  |  |
Number Of Metro Signals |  |  |  |  |  |  |  |  |  |  | 78 |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares |  |  |  |  |  |  |  |  |  |  | 0 | 0 | 0 |  |  |  |  |
Number of Reportable Segments | segment |  |  |  |  |  |  |  |  |  |  | 1 |  |  |  |  |  |  |
Concentration Risk, Market Risk |  |  |  |  |  |  |  |  |  |  | 39.00% | 39.00% | 41.00% |  |  |  |  |
Time deposits |  |  |  |  |  |  |  |  |  |  |  | $ 0 | $ 0 | $ 0 |  |  |  |
Interest expense related to the amortization of debt issuance costs |  |  |  |  |  |  |  |  |  |  | $ 40,000 | 103,000 | 51,000 |  |  |  |  |
Write-off of debt issuance costs |  |  |  |  |  |  |  |  |  |  | $ 40,000 | 103,000 | $ 51,000 |  |  |  |  |
Net book value of deferred costs |  |  |  |  |  |  |  |  |  |  |  | $ 104,000 |  | 64,000 |  |  |  |
Treasury Stock, Shares, Acquired | shares |  |  |  |  |  |  |  |  |  |  | 24,255 | 39,505 | 53,713 |  |  |  |  |
Treasury Stock Acquired, Average Cost Per Share | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 18.51 | $ 29.68 | $ 37.24 |  |  |  |  |
Cash dividend paid | $ / shares |  |  |  |  |  |  |  |  | $ 0.30 |  |  |  |  |  |  |  |  |
Dividend paid | $ 1,900,000 | $ 1,800,000 | $ 1,800,000 | $ 1,800,000 |  | $ 1,800,000 | $ 1,800,000 | $ 1,800,000 | $ 3,300,000 | $ 1,800,000 |  |  |  |  |  |  |  |
Number Of Broadcast Licenses |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 114 |  |  |
Number Of Market Serving |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 27 | 27 |  |
Debt Issuance Costs, Net |  |  |  |  |  |  |  |  |  |  |  |  | $ 120,000 |  |  |  |  |
Operating Lease, Right-of-Use Asset |  |  |  |  |  |  |  |  |  |  |  | $ 6,900,000 |  | 6,600,000 |  |  |  |
Operating Lease, Liability, Statement of Financial Position [Extensible List] |  |  |  |  |  |  |  |  |  |  | Other Liabilities, Noncurrent | Other Liabilities, Noncurrent |  |  |  |  |  |
Operating Lease, Liability |  |  |  |  |  |  |  |  |  |  |  | $ 7,000,000.0 |  | 6,949,000 |  |  |  |
Number of operating segments | segment |  |  |  |  |  |  |  |  |  |  | 1 |  |  |  |  |  |  |
Customer relationships [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |  |  |  |
Continuing Operations [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Depreciation expense |  |  |  |  |  |  |  |  |  |  | $ 5,711,000 | 5,916,000 | 5,692,000 |  |  |  |  |
Advertising and promotion costs |  |  |  |  |  |  |  |  |  |  | $ 985,000 | $ 2,442,000 | $ 2,438,000 |  |  |  |  |
Class A Common Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock Repurchase Program, Remaining Authorized Repurchase Amount |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 18,800,000 |  |  |  |
Common Class A and Common Class B |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash dividend paid | $ / shares | $ 0.32 | $ 0.30 | $ 0.30 |  | $ 0.30 | $ 0.30 | $ 0.30 | $ 0.30 | $ 0.25 | $ 0.30 |  |  |  |  |  |  |  |
Minimum [Member] | Lease Agreements [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  |  |  |  |  |  |  |  |  |  | 1 year |  |  |  |  |  |  |
Minimum [Member] | Other intangibles [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  |  |  |  |  |  |  |  |  |  | 1 year |  |  |  |  |  |  |
Minimum [Member] | Class A Common Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock Repurchase Program, Authorized Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 60,000,000
Maximum [Member] | Lease Agreements [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  |  |  |  |  |  |  |  |  |  | 26 years |  |  |  |  |  |  |
Maximum [Member] | Other intangibles [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  |  |  |  |  |  |  |  |  |  | 15 years |  |  |  |  |  |  |
Maximum [Member] | Class A Common Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock Repurchase Program, Authorized Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 75,800,000 |

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