Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions	1 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2015	Mar. 31, 2015
Disclosure - Stockholders' Equity - Additional Information (Detail) [Line Items]
Common stock issued as a result of option exercises			0.3
Value of shares authorized to repurchase program				$ 750,000,000
Shares repurchased		1.3	4.1
Average price per share for common shares repurchased		$ 76.64	$ 79.55
Total cost of common shares repurchased		$ 100,000,000	$ 328,000,000
Remaining capacity for authorized repurchase shares	$ 501,000,000	$ 501,000,000	501,000,000
Dividends paid	$ 64,000,000		$ 192,000,000
Dividends paid per share	$ 0.375		$ 1.125
Dividends record date	Sep. 11, 2015
Maximum [Member]
Disclosure - Stockholders' Equity - Additional Information (Detail) [Line Items]
Common stock issued as a result of option exercises		0.1