Business Segments (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 segments	Jun. 30, 2013
Disclosure Business Segments Summary Of Companys Segment Results [Abstract]
Number of principal business operations			3
Extinguishment Of Debt [Line Items]
Net gains (losses) on extinguishment of debt	$ 2	$ 39	$ 3	$ 43
Medium Term Notes [Member]
Extinguishment Of Debt [Line Items]
Retired medium-term notes			129
Net gains (losses) on extinguishment of debt			$ 4