Share-Based Compensation Expense (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense	$ 32	[1]	$ 27	[1]
Unrecognized share-based compensation	$ 90				$ 44

[1] Includes $3 million and $8 million of expense recognized in merger integration-related costs for the three months ended March 31, 2014 and 2013, respectively.