Losses associated with the earthquake in Japan (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		13 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012
Operating income (loss)	$ 397	$ 908
Revenue	3,121	3,392
Earthquake in Japan, March 11, 2011 [Member]
Operating income (loss)	0	(30)	(101)
Insurance Settlement, Property Damage Claims [Member] | Earthquake in Japan, March 11, 2011 [Member]
Operating income (loss)			23
Insurance Settlement, Business Interruption Claims [Member] | Earthquake in Japan, March 11, 2011 [Member]
Revenue	$ 65		$ 100