Accounts and Notes Receivable and Credit Quality of Notes Receivable (Modification of Terms) (Details) (Notes receivable, USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015 contract customer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of customers	3
Number of notes	9
Pre-modification investment	$ 7.0
Post-modification investment	7.0
International
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of customers	3	[1]
Number of notes	9	[1]
Pre-modification investment	7.0	[1]
Post-modification investment	7.0	[1]
International | Customer one
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of customers	1
Post-modification investment	3.1
Number of notes consolidated into one	3
Contract extension term	4 months
International | Customer two
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of customers	1
Post-modification investment	2.3
Contract extension term	9 months
International | Customer Three
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of customers	1
Number of notes consolidated into one	4
International | Customer three, note one
Accounts, Notes, Loans and Financing Receivable [Line Items]
Post-modification investment	1.4
Number of notes consolidated into one	1
Contract extension term	5 months
International | Customer three, note two
Accounts, Notes, Loans and Financing Receivable [Line Items]
Post-modification investment	$ 0.2
Contract extension term	7 months

[1] The modifications are detailed below: •one customer for which three notes were consolidated into one note aggregating $3.1 million, with an average four-month payment extension; •one customer with a note for $2.3 million for which original payment terms were extended by nine months; and•one customer for which four notes were consolidated into one note aggregating $1.4 million, with an average five-month extension, and another note for $0.2 million for which original payment terms were extended by seven months.