Severance, Exit Costs and Asset Impairments (Schedule of Severance and Exit Costs) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2008
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 244	$ 79	$ 94	$ 199
Exit Cost, Net Expense (Benefit)		0	25
Severance Cost, Net Expense (Benefit)	0	(28)	17
Total severance and exit costs, Net Expense (Benefit)	240	28	8
Exit costs, Cash Payments and Other		(29)	(27)
Severance cost, Cash Payments and Other	(10)	(14)	(86)
Total severance and exit costs, Cash Payments and Other	(75)	43	113
Exit cost			87	89
Severance Cost	11	21	7	110
Lease [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	190	58
Total severance and exit costs, Net Expense (Benefit)	196
Restructuring reserved settled with cash and other adjustments	(64)
Access [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	43	0
Total severance and exit costs, Net Expense (Benefit)	44
Restructuring reserved settled with cash and other adjustments	$ (1)