Other Assets (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Other assets
Other assets	$ 126.5	$ 36.3
Write-off of unamortized deferred financing fees	5.9	7.6	4.2
Deferred financing costs
Other assets
Other assets	92.5	25.5
Capitalized costs during period	92.1	6.3	14.5
Amortization expense for period	7.8	7.1	7.5
Deferred tax asset, long-term portion
Other assets
Other assets	22.6	6.3
Other assets
Other assets
Other assets	$ 11.4	$ 4.5