Commitments and Contingencies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016 USD ($) ft²	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Contingencies And Commitments [Line Items]
Lease commitment with media research and rating providers, aggregate amount	$ 27,500,000
Non-cancelable operating lease expiration term	2016-12
Total rent expense under operating leases	$ 11,000,000	$ 10,900,000	$ 9,900,000
Santa Monica
Contingencies And Commitments [Line Items]
Area under operating leases for corporate headquarters | ft²	16,000
Lease Expiration Year	2021
Los Angeles
Contingencies And Commitments [Line Items]
Area under operating leases for corporate headquarters | ft²	41,000
Lease Expiration Year	2026
Facilities and Broadcast Equipment
Contingencies And Commitments [Line Items]
Non-cancelable operating lease expiration term	2059-12
Minimum
Contingencies And Commitments [Line Items]
Lease commitment with media research and rating providers, annual commitment range	$ 4,700,000
Maximum
Contingencies And Commitments [Line Items]
Lease commitment with media research and rating providers, annual commitment range	$ 11,600,000