Supplemental Condensed Consolidating Financial Information and Other Collateral-Related Information - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Oct. 31, 2012	Nov. 22, 2010	Dec. 31, 2013 Senior Unsecured Notes Due 2021 [Member]	Dec. 31, 2012 Senior Unsecured Notes Due 2021 [Member]	Dec. 06, 2012 Senior Unsecured Notes Due 2021 [Member]	Nov. 23, 2010 Senior Unsecured Notes Due 2021 [Member]
Supplemental Condensed Consolidating Financial Information [Line Items]
Debt instrument, principal amount	$ 2,500		$ 1,000	$ 1,000	$ 1,000	$ 1,525
Debt instrument, stated interest				6.25%	6.25%	7.75%
Ownership percentage held by parent		100.00%