Supplemental Condensed Consolidating Financial Information - Additional Information (Detail) - USD ($) $ in Millions	May. 31, 2015	Dec. 31, 2012	Nov. 30, 2010	Nov. 23, 2010
Supplemental Condensed Consolidating Financial Information [Line Items]
Ownership percentage held by parent				100.00%
Senior Unsecured Notes Due 2021 [Member]
Supplemental Condensed Consolidating Financial Information [Line Items]
Debt instrument, principal amount		$ 1,000	$ 1,525
Debt instrument, stated interest	7.75%	6.25%	7.75%
Debt instrument, redeemed amount	$ 1,525