Commitments and Contingencies (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Commitments and Contingencies (Textual) [Abstract]
Lease commitment with media research and rating providers, aggregate amount	$ 31.7
Total rent expense under operating leases	10.2	10.1	10.4
Bonus paid to executives	0.5	0	0.3
Minimum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Lease commitment with media research and rating providers, Annual Commitment Range	6.8
Maximum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Lease commitment with media research and rating providers, Annual Commitment Range	$ 12.6
Santa Monica [Member]
Property Subject to or Available for Operating Lease [Line Items]
Area under operating leases for corporate headquarters	16,000
Lease Expiration Year	2021
Los Angeles [Member]
Property Subject to or Available for Operating Lease [Line Items]
Area under operating leases for corporate headquarters	45,000
Lease Expiration Year	2016