Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Summary Of Significant Accounting Policies [Line Items]
Marketing and advertising costs	$ 169.1	$ 160.4	$ 144.5
Contractual Relationship [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	20 years
Customer and advertiser lists [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	25 years
Trade Names [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	25 years
Other Intangible Assets [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	25 years