Debt - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended		6 Months Ended		9 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Jun. 30, 2014 Coupon Rate of 1.3% Notes Mature in June 2017 [Member]	Jun. 30, 2014 Coupon Rate of 3.5% Notes Mature in July 2024 [Member]	Sep. 30, 2014 Unsecured Fixed-Rate Notes [Member]	Sep. 30, 2014 WilcoHess [Member]
Debt Instrument [Line Items]
Unsecured fixed-rate notes issued		$ 600	$ 300	$ 300
Unsecured fixed-rate notes issued, net of discount		598
Coupon rate			1.30%	3.50%
Debt notes maturity period			Jun. 30, 2017	Jul. 31, 2024
Repayments of debt	553				250	74
Retirement of various lease obligations	$ 212