Accounts and Notes Receivable and Credit Quality of Notes Receivable - Components of Current and Long-term Accounts and Notes Receivable, Net (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Current:
Accounts receivable	$ 330.2	$ 360.4
Notes receivable	150.5	164.3
Allowance for doubtful accounts	(19.0)	(20.0)
Current accounts and notes receivable, net	461.7	504.7
Long-term:
Notes receivable	64.1	72.6
Accounts and notes receivable, net	$ 525.8	$ 577.3