Additional Information about Derivative Assets and Liabilities Subject to Enforceable Master Netting Arrangement (Parenthetical) (Detail) (Subject to enforceable master netting arrangement, USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Derivative assets
Derivative [Line Items]
Net amounts presented in the balance sheet, accruals on derivative assets	$ 1,157	[1]	$ 496	[1]
Derivative assets | Other assets
Derivative [Line Items]
Net amounts presented in the balance sheet, accruals on derivative assets	25		25
Derivative liabilities
Derivative [Line Items]
Net amounts presented in the balance sheet, accruals on derivative liabilities	273	[2]	662	[2]
Derivative liabilities | Other liabilities
Derivative [Line Items]
Net amounts presented in the balance sheet, accruals on derivative liabilities	$ 6		$ 7

[1] Included $25 million of accruals on derivatives classified as other assets and does not include amounts related to embedded derivatives as of December 31, 2014 and 2013.

[2] Included $6 million and $7 million of accruals on derivatives classified as other liabilities and does not include amounts related to embedded derivatives and derivatives related to securitization entities as of December 31, 2014 and 2013, respectively.