Quarterly report pursuant to Section 13 or 15(d)

Recent Transactions - Pending Transactions -Additional Information (Detail)

v3.20.2
Recent Transactions - Pending Transactions -Additional Information (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 10, 2020
Apr. 06, 2020
Feb. 05, 2020
Dec. 31, 2020
Mar. 31, 2020
Sep. 30, 2020
Sep. 30, 2019
Dec. 31, 2019
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]                
Agreement to sell business           $ 188 $ 4,202  
Additional Term Of Time Brokerage Agreement     30 months          
Radio Stations [Member]                
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]                
Agreement to sell business $ 3,500 $ 200 $ 4,000          
Pretax loss on sale of assets       $ 1,400       $ 1,500
Credit applied to the sale price     $ 250,000          
Time brokerage agreement fees         $ 2,000      
Line of credit facility, option payment         $ 450,000