Securities Financing Activities - Summarized Securities Financing Agreements (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Securities Financing Transaction [Line Items]
Reverse repurchase agreements	$ 0
Total	0
Repurchase agreements	0
Total	0
Counterparty And Cash Collateral Netting [Member]
Securities Financing Transaction [Line Items]
Reverse repurchase agreements	0
Total	0
Repurchase agreements	(252)
Total	(252)
Federal Agency CMOs [Member]
Securities Financing Transaction [Line Items]
Assets pledged as collateral	409
Liabilities pledged as collateral	252
Gross Amounts Presented In Balance Sheets [Member]
Securities Financing Transaction [Line Items]
Reverse repurchase agreements	11	$ 3
Total	11
Repurchase agreements	266
Total	266
Netting Adjustments [Member]
Securities Financing Transaction [Line Items]
Reverse repurchase agreements	(11)
Total	(11)
Repurchase agreements	(14)
Total	$ (14)

Offsetting of financial assets.

No definition available.

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- Definition

Offsetting of financial liabilities.

+ References

No definition available.

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- Definition

Sum of the carrying amounts as of the date of the latest financial statement presented of securities which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The carrying value of securities purchased to be resold in reverse repurchase transactions as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(m)(2)(i))
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- Definition

Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

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- Definition

Fair value of liabilities arising from or related to a financial instrument held by the entity for its own account (proprietary securities) which has been pledged to counterparties.

+ References

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-Publisher FASB
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-Topic 320
-SubTopic 10
-Section 50
-Paragraph 1B
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