The Company and Significant Accounting Policies - Fair Value Assets and Liabilities Measured on Recurring Basis and Nonrecurring Basis (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Sep. 30, 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	$ 63.8	$ 21.6
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	1.4	0.4
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	44.5	17.4
Fair Value, Measurements, Recurring | Asset-Backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Carrying Value on Assets		0.6
Fair Value, Measurements, Recurring | U.S. Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Carrying Value on Assets		0.1
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	1.4	0.4
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	44.5	17.4
Fair Value, Measurements, Recurring | Level 2 | Asset-Backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Carrying Value on Assets		0.6
Fair Value, Measurements, Recurring | Level 2 | U.S. Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Carrying Value on Assets		0.1
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 Liabilities	63.8
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	24.5
Total Gains (Losses)	(1.6)
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	$ 24.5	$ 21.6