Annual report pursuant to Section 13 and 15(d)

Broadcast Licenses - Fair Value Measurement Inputs and Valuation Techniques for Broadcast Licenses (Detail)

v3.20.4
Broadcast Licenses - Fair Value Measurement Inputs and Valuation Techniques for Broadcast Licenses (Detail) - Broadcast Licenses [Member]
Dec. 31, 2020
Sep. 30, 2020
Mar. 31, 2020
Dec. 31, 2019
Measurement Input, Risk-adjusted Discount Rate [Member]        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Intangible asset measurement input percentage 0.085 0.085 0.095 0.090
Minimum [Member] | Measurement Input, Operating Profit Margin [Member]        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Intangible asset measurement input percentage 0.310 0.333 0.338 0.338
Minimum [Member] | Measurement Input, Long-term Revenue Growth Rate [Member]        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Intangible asset measurement input percentage 0.004 0.002 0.008 0.007
Maximum [Member] | Measurement Input, Operating Profit Margin [Member]        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Intangible asset measurement input percentage 0.042 0.043 0.046 0.040
Maximum [Member] | Measurement Input, Long-term Revenue Growth Rate [Member]        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Intangible asset measurement input percentage 0.009 0.011 0.011 0.011