Operating Leases (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating Leases
Rent expense attributable to warehouse, office buildings and equipment operating leases	$ 76	$ 89	$ 115
Minimum future rentals under operating leases
2013	52
2014	42
2015	33
2016	26
2017	18
2018 and thereafter	$ 35