Supplemental Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Allowance for Doubtful Accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 29	[1]	$ 25	[1]	$ 24	[1]
Additions charged to expense	4		11		6
Deductions	(8)		(7)		(5)
Balance at end of year	25		29	[1]	25	[1]
Inventory Valuation
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	39	[1]	33	[1]	43	[1]
Additions charged to expense	9		17		9
Deductions	(10)		(11)		(19)
Balance at end of year	$ 38		$ 39	[1]	$ 33	[1]

[1] During the fourth quarter of 2012, the Company changed its method of accounting for those inventories which were accounted for under the LIFO method to the FIFO method. See Note 1 for discussion of this accounting change and its related impact.