Stockholders' Equity (Narrative) (Detail) - USD ($) shares in Millions, $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Stockholders Equity [Line Items]
Stock Repurchase Program, Authorized Amount		$ 635
Stock Repurchased During Period, Shares	3.0	2.2
Stock Repurchased During Period, Value		$ 116	$ 150
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 169