Additional Information about Derivative Assets and Liabilities Subject to Enforceable Master Netting Arrangement (Detail) - USD ($) $ in Millions		Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Gross amounts recognized, derivatives assets		$ 198	$ 290
Gross amounts recognized, derivatives liabilities		906	730
Subject to enforceable master netting arrangement
Derivative [Line Items]
Gross amounts recognized, net derivatives		16	231
Gross amounts offset in the balance sheet, net derivatives		0	0
Net amounts presented in the balance sheet, net derivatives		16	231
Gross amounts not offset in the balance sheet, financial instruments, net derivatives	[1]	0	0
Collateral received		(84)	(170)
Collateral pledged		536	288
Over collateralization, net derivatives		(423)	(264)
Net amount		45	85
Subject to enforceable master netting arrangement | Derivative assets
Derivative [Line Items]
Gross amounts recognized, derivatives assets	[2]	185	278
Gross amounts offset in the balance sheet, derivatives assets	[2]	0	0
Net amounts presented in the balance sheet, derivatives assets		185	278	[2]
Gross amounts not offset in the balance sheet, financial instruments, derivatives assets	[1],[2]	(66)	(23)
Collateral received	[2]	(84)	(170)
Over collateralization, derivatives assets	[2]	10	0
Net amount, derivatives assets	[2]	45	85
Subject to enforceable master netting arrangement | Derivative liabilities
Derivative [Line Items]
Gross amounts recognized, derivatives liabilities	[3]	169	47
Gross amounts offset in the balance sheet, derivatives liabilities	[3]	0	0
Net amounts presented in the balance sheet, derivatives liabilities	[3]	169	47
Gross amounts not offset in the balance sheet, financial instruments, derivative liabilities	[1],[3]	(66)	(23)
Collateral pledged	[3]	(536)	(288)
Over collateralization, derivatives liabilities	[3]	433	264
Net amount, derivatives liabilities	[3]	$ 0	$ 0

[1] Amounts represent derivative assets and/or liabilities that are presented gross within the balance sheet but are held with the same counterparty where we have a master netting arrangement. This adjustment results in presenting the net asset and net liability position for each counterparty.

[2] Included $6 million and $2 million of accruals on derivatives classified as other assets and does not include amounts related to embedded derivatives as of December 31, 2018 and 2017, respectively.

[3] Does not include amounts related to embedded derivatives and derivatives related to securitization entities as of December 31, 2018 and 2017.