Business Segments (Narrative) (Detail) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)
Disclosure Business Segments Summary Of Companys Segment Results [Abstract]
Number of operating segments		3
Extinguishment Of Debt [Line Items]
Net gains (losses) on extinguishment of debt	$ 0	$ (1)	$ 3