Accounting Policies - Allowance for Losses (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2012 contract	Jun. 30, 2012 contract
Financing Receivable, Modifications [Line Items]
Loans receivable allowance calculation period		3 years
Impaired loans receivable past due period minimum		90 days
Financing Loans
Financing Receivable, Modifications [Line Items]
Before restructuring investment recorded during the period	$ 0.1	$ 1.1
After restructuring investment recorded during the period	0.1	1.3
Number of defaulted contracts	1	1
Defaulted contract recorded investment	0.1	0.1
Impaired troubled debt restructuring allowance write-down	$ 0.2	$ (0.2)