Debt - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013 Unsecured Floating Rate Euro Denominated Export Credit Facility [Member]	Aug. 31, 2013 Unsecured Floating Rate Export Credit Facilities [Member]	Jul. 31, 2013 Unsecured Floating Rate Bank Loan [Member]	Feb. 28, 2013 Unsecured Publicly-Traded Notes	Dec. 31, 2012 Unsecured Publicly-Traded Notes	Aug. 31, 2013 Unsecured Floating Rate Euro Denominated Revolving Bank Loan Facility [Domain]	Sep. 30, 2013 Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Issuance of unsecured publicly-traded notes	$ 311			$ 500	$ 500
Debt instrument, interest rate				1.20%	1.90%
Unsecured long-term debt		$ 526	$ 150			$ 265	$ 300