Accounts Receivable, Notes Receivable, Allowance for Doubtful Accounts and Bad Debt - Evaluation of Notes Receivable For Impairment (Details) (Notes Receivable, USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
Notes receivable	$ 282.1	$ 236.9
Ending balance individually evaluated for impairment	157.1	104.5
Ending balance collectively evaluated for impairment	125.0	132.4
Domestic
Financing Receivable, Recorded Investment, Past Due [Line Items]
Notes receivable	95.3	65.1
Ending balance individually evaluated for impairment	36.1	4.8
Ending balance collectively evaluated for impairment	59.2	60.3
International
Financing Receivable, Recorded Investment, Past Due [Line Items]
Notes receivable	186.8	171.8
Ending balance individually evaluated for impairment	121.0	99.7
Ending balance collectively evaluated for impairment	$ 65.8	$ 72.1