Accounts and Notes Receivable and Credit Quality of Notes Receivable - Allowance for Doubtful Accounts Receivable (Details) (Notes Receivable, USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Notes Receivable
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance at December 31, 2013	$ 5.6
Charge-offs	0
Recoveries	0
Provision	1.0
Ending Balance at March 31, 2014	6.6
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment [Roll Forward]
Beginning balance at December 31, 2013	5.6
Charge-offs	0
Recoveries	0
Provision	0.9
Ending Balance at March 31, 2014	6.5
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment [Roll Forward]
Beginning balance at December 31, 2013	0
Charge-offs	0
Recoveries	0
Provision	0.1
Ending Balance at March 31, 2014	$ 0.1