Income Tax Expense - Gross Unrecognized Income Tax Benefits (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of Gross Unrecognized Income Tax Benefits [Roll Forward]
Balance at January 1	$ 2.7	$ 11.4	$ 12.3
Additions for Tax Positions Related to the Current Year	0.1	0	0
Additions for Tax Positions Related to Prior Years	1.3	0	0
Reduction for Tax Positions Related to Prior Years	0	(8.7)	(0.9)
Reductions for Settlements	(2.9)	0	0
Balance as of December 31	1.2	2.7	11.4
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	0.2
Unrecognized Tax Benefits, Accrued Interest	0.5	0.5	1.1
Unrecognized Tax Benefits, Penalties	0	0	0
Unrecognized Tax Benefits, Interest Expense (Reduction)	0	(0.6)	0.4
Reasonably Possible Change in Unrecognized Tax Benefits in Next 12 Months	$ 0.2