Stockholders' Equity - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Mar. 31, 2013
Equity [Abstract]
Common stock issued as a result of option exercises	530,000	2,100,000
Value of shares authorized to repurchase program			$ 500
Shares repurchased	140,000	950,000
Average price per share for common shares repurchased	$ 59.77	$ 59.35
Total cost of common shares repurchased	8	56
Remaining capacity for authorized repurchase shares		$ 624