Fair Value Measurements (Fair Value Hierarchy Classification) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2014 Estimate of Fair Value, Fair Value Disclosure [Member]	Dec. 31, 2013 Estimate of Fair Value, Fair Value Disclosure [Member]	Mar. 31, 2014 Estimate of Fair Value, Fair Value Disclosure [Member] Quoted price in active markets (Level 1) [Member]	Mar. 31, 2014 Estimate of Fair Value, Fair Value Disclosure [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2014 Estimate of Fair Value, Fair Value Disclosure [Member] Unobservable inputs (Level 3) [Member]	Mar. 31, 2014 Portion at Other than Fair Value Measurement [Member]	Dec. 31, 2013 Portion at Other than Fair Value Measurement [Member]	Mar. 31, 2014 Fair Value, Measurements, Recurring [Member]	Dec. 31, 2013 Fair Value, Measurements, Recurring [Member]	Mar. 31, 2014 Fair Value, Measurements, Recurring [Member] Quoted price in active markets (Level 1) [Member]	Dec. 31, 2013 Fair Value, Measurements, Recurring [Member] Quoted price in active markets (Level 1) [Member]	Mar. 31, 2014 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2013 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2014 Fair Value, Measurements, Recurring [Member] Unobservable inputs (Level 3) [Member]	Dec. 31, 2013 Fair Value, Measurements, Recurring [Member] Unobservable inputs (Level 3) [Member]	Mar. 31, 2014 Fair Value, Measurements, Nonrecurring [Member]	Dec. 31, 2013 Fair Value, Measurements, Nonrecurring [Member]	Mar. 31, 2014 Fair Value, Measurements, Nonrecurring [Member] Quoted price in active markets (Level 1) [Member]	Dec. 31, 2013 Fair Value, Measurements, Nonrecurring [Member] Quoted price in active markets (Level 1) [Member]	Mar. 31, 2014 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2014 Fair Value, Measurements, Nonrecurring [Member] Unobservable inputs (Level 3) [Member]	Dec. 31, 2013 Fair Value, Measurements, Nonrecurring [Member] Unobservable inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure									$ 866	$ 988	$ 866	$ 988	$ 0	$ 0	$ 0	$ 0
Derivative Assets									118	90	0	0	118	90	0	0
Derivative Financial Instruments, Liabilities, Fair Value Disclosure									(226)	(157)	0	0	(226)	(157)	0	0
Business Dispositions, Fair Value Disclosure																	55	66	0	0	55	66	0	0
Long-term receivables Fair Value Disclosure		651	586	0	651	0	752	655
Customer Financing Notes Receivable Fair Value Disclosure		276	366	0	276	0	291	394
Short Term borrowings		(188)	(388)	0	0	(188)	(188)	(388)
Long-term debt (excluding capitalized leases) Fair Value Disclosure		(22,041)	(21,525)	0	(21,716)	(325)	(19,808)	(19,807)
Other long-term liabilities, Fair Value Disclosure		(268)	(253)	0	(268)	0	(304)	(283)
Gain (Loss) on Disposition of Business	$ 38