Earnings per Share - Computation of Basic and Diluted Earnings per Share (EPS) (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Change in net income for purposes of computing diluted earnings per share	$ (2)	$ 3
Convertible Senior Notes, 7.25, Due in 2014 [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Debt instrument, stated interest rate percentage	7.25%	7.25%	7.25%