Summary of Significant Accounting Policies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accounting policies
Maximum original maturity period of highly liquid debt instruments to be considered as cash equivalents	3 months
Gain on sale of property and equipment	$ 3.9	$ 8.3	$ 43.5
Foreign currency translation gain	54.8	102.3
Advertising costs	213.1	183.9	168.2
Direct Operating Expense
Accounting policies
Gain on sale of property and equipment	$ 3.9	$ 8.3