Other Information - Barter and Trade Revenues and Expenses from Continuing Operations (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Barter and trade revenues	$ 31.0	$ 19.9	$ 87.6	$ 54.2
Barter and trade expenses	$ 31.0	$ 22.7	$ 84.1	$ 55.1