Intangible Assets and Goodwill - Intangible Assets Narrative (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, net	$ 70.9		$ 70.9		$ 81.9
Amortization expense	$ 3.4	$ 7.2	$ 10.3	$ 21.7