Annual report pursuant to Section 13 and 15(d)

Broadcast Licenses - Carrying Value and Fair Value of Broadcast Licenses (Detail)

v3.20.4
Broadcast Licenses - Carrying Value and Fair Value of Broadcast Licenses (Detail) - Broadcast Licenses [Member]
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2020
USD ($)
Accounting
Dec. 31, 2020
USD ($)
Accounting
Less than or equal to 25% [Member]    
Indefinite-lived Intangible Assets [Line Items]    
Number Of Business Reporting Units For Market Based Services | Accounting 11 4
Excess Of Estimated Undiscounted Cash Flows Over Carrying Value | $ $ 188,858 $ 92,983
>26%-50% [Member]    
Indefinite-lived Intangible Assets [Line Items]    
Number Of Business Reporting Units For Market Based Services | Accounting   8
Excess Of Estimated Undiscounted Cash Flows Over Carrying Value | $   $ 44,670
>26%-50% [Member] | Station Operating Income [Member]    
Indefinite-lived Intangible Assets [Line Items]    
Number Of Business Reporting Units For Market Based Services | Accounting   3
Excess Of Estimated Undiscounted Cash Flows Over Carrying Value | $   $ 13,373
>51% to 75% [Member]    
Indefinite-lived Intangible Assets [Line Items]    
Number Of Business Reporting Units For Market Based Services | Accounting   2
Excess Of Estimated Undiscounted Cash Flows Over Carrying Value | $   $ 27,465
>51% to 75% [Member] | Station Operating Income [Member]    
Indefinite-lived Intangible Assets [Line Items]    
Number Of Business Reporting Units For Market Based Services | Accounting   2
Excess Of Estimated Undiscounted Cash Flows Over Carrying Value | $   $ 8,150
> than 76% [Member]    
Indefinite-lived Intangible Assets [Line Items]    
Number Of Business Reporting Units For Market Based Services | Accounting   1
Excess Of Estimated Undiscounted Cash Flows Over Carrying Value | $   $ 6,092
> than 76% [Member] | Station Operating Income [Member]    
Indefinite-lived Intangible Assets [Line Items]    
Number Of Business Reporting Units For Market Based Services | Accounting   8
Excess Of Estimated Undiscounted Cash Flows Over Carrying Value | $   $ 63,869