Stock-Based Compensation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2013 2004 and 2013 Long Term Incentive Plan [Member]	Jun. 30, 2013 2004 and 2013 Long Term Incentive Plan [Member]	Jun. 30, 2012 2004 Long-Term Incentive Compensation Plan [Member]	Jun. 30, 2013 2004 Long-Term Incentive Compensation Plan [Member]	Jun. 30, 2012 2004 Long-Term Incentive Compensation Plan [Member]	May 31, 2013 2004 Long-Term Incentive Compensation Plan [Member] Maximum [Member]	Jun. 30, 2013 2013 Long-Term Incentive Compensation Plan [Member] Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted during the period				164,000
Grant date fair value of per share				$ 77.72
Restricted stock units granted during the period				1,175,000
Restricted stock and units granted, weighted average grant date fair value per share or unit				$ 60.30
Aggregate number of shares available for grant						56,000,000	11,000,000
Compensation expense, net of reimbursements	$ 14	$ 27	$ 16		$ 34
Unrecognized compensation cost of nonvested options and restricted stock, net of estimated forfeitures	$ 91	$ 91
Weighted-average period of unrecognized compensation cost, expected to be recognized		1 year 9 months 29 days