Debt and Financing Cost - Additional Information (Detail) (USD $)	6 Months Ended					6 Months Ended		3 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014 United States [Member]	Jun. 30, 2014 Australia [Member]	Jun. 30, 2014 Canada [Member]	Jun. 30, 2014 Revolving Credit Facility Due August 2016 [Member]	Jun. 30, 2014 Revolving Credit Facility Due June 2018 [Member]	Jun. 30, 2014 Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Unsecured credit facility available to Company	$ 3,300,000,000					$ 1,000,000,000	$ 2,300,000,000
Credit facility maturity date						Aug. 31, 2016	Jun. 30, 2018
Revolving bank facility	1,700,000,000		1,000,000,000	300,000,000	300,000,000
Line of credit facility, remaining borrowing capacity	3,300,000,000
Financing period extension period	1 year
Commercial paper program	3,000,000,000
Period For Borrowing Funds								270 days
Carrying Amount, Commercial paper	0	0
Current debt	$ 1,000,000	$ 53,000,000