The Company and Significant Accounting Policies - Fair Value Assets and Liabilities Measured on Recurring Basis and Nonrecurring Basis (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Measurements, Recurring | Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Carrying Value on Liabilities	$ 25.7	$ 28.0
Fair Value, Measurements, Recurring | Money Market Account
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Carrying Value on Assets	0.2	1.1
Fair Value, Measurements, Recurring | Corporate Bonds and Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Carrying Value on Assets	4.3	13.2
Fair Value, Measurements, Recurring | Level 1 | Money Market Account
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Carrying Value on Assets	0.2	1.1
Fair Value, Measurements, Recurring | Level 2 | Corporate Bonds and Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Carrying Value on Assets	4.3	13.2
Fair Value, Measurements, Recurring | Level 3 | Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Carrying Value on Assets	25.7
Fair Value and Carrying Value on Liabilities		28.0
Fair Value, Measurements, Nonrecurring | FCC Licenses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Carrying Value on Assets		27.6
Total Gains (Losses)		(12.3)
Fair Value, Measurements, Nonrecurring | Digital Reporting Unit Goodwill
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Carrying Value on Assets	14.7
Total Gains (Losses)	(35.4)
Fair Value, Measurements, Nonrecurring | Level 3 | FCC Licenses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Carrying Value on Assets		$ 27.6
Fair Value, Measurements, Nonrecurring | Level 3 | Digital Reporting Unit Goodwill
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Carrying Value on Assets	$ 14.7