Credit Quality of Long-term Receivables (Class and Credit Risk Information) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	$ 1,211	$ 1,177
Long-term Trade Accounts Receivable Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	608	593
Notes And Leases Receivable Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	603	584
A Low Risk Internally Assigned Grade [Member] | Long-term Trade Accounts Receivable Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	584	569
A Low Risk Internally Assigned Grade [Member] | Notes And Leases Receivable Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	32	26
B Moderate Risk Internally Assigned Grade [Member] | Long-term Trade Accounts Receivable Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	21	21
B Moderate Risk Internally Assigned Grade [Member] | Notes And Leases Receivable Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	427	458
C High Risk Internally Assigned Grade [Member] | Long-term Trade Accounts Receivable Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	3	3
C High Risk Internally Assigned Grade [Member] | Notes And Leases Receivable Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	144	100
D In Default Uncollateralized Internally Assigned Grade [Member] | Long-term Trade Accounts Receivable Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0
D In Default Uncollateralized Internally Assigned Grade [Member] | Notes And Leases Receivable Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	$ 0	$ 0