Amortization of Definite Lived Intangible Assets in Asset Exchange, in Relation to Expected Economic Benefits of Such Assets (Detail) (Advertising Relationships, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Advertising Relationships
Component of Operating Other Cost and Expense [Line Items]
Estimated Useful Life in Years	6 years
Fair Value	$ 200