Annual report pursuant to Section 13 and 15(d)

Recent Transactions - Pending Transactions -Additional Information (Detail)

v3.20.4
Recent Transactions - Pending Transactions -Additional Information (Detail) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Sep. 10, 2020
Apr. 06, 2020
Feb. 05, 2020
Dec. 31, 2020
Dec. 31, 2020
Dec. 31, 2019
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]            
Agreement to sell business         $ 189 $ 20,741
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