Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Contingencies And Commitments [Line Items]
Lease commitment with media research and rating providers, aggregate amount	$ 18,100,000
Non-cancelable operating lease expiration term	2016-12
Total rent expense under operating leases	9,900,000	9,800,000	10,200,000
Bonus paid to executives	200,000	200,000	500,000
Santa Monica
Contingencies And Commitments [Line Items]
Area under operating leases for corporate headquarters	16,000
Lease Expiration Year	2021
Los Angeles
Contingencies And Commitments [Line Items]
Area under operating leases for corporate headquarters	45,000
Lease Expiration Year	2026
Facilities and Broadcast Equipment
Contingencies And Commitments [Line Items]
Non-cancelable operating lease expiration term	2059-09
Minimum
Contingencies And Commitments [Line Items]
Lease commitment with media research and rating providers, annual commitment range	5,800,000
Maximum
Contingencies And Commitments [Line Items]
Lease commitment with media research and rating providers, annual commitment range	$ 12,300,000