Fair Value Measurements (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Parenthetical) (Detail) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Federal Home Loan Bank Stock	$ 248	$ 248
Federal Reserve Bank Stock	362	362
DTCC Stock	$ 2	$ 2

Represents an equity interest in Depository Trust Clearing Corporation. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity).

No definition available.

+ Details

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Period Type:	instant

- References

No definition available.

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- Definition

Federal Home Loan Bank (FHLB) stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 325
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=75031641&loc=d3e63345-112809

+ Details

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- Definition

Federal Reserve Bank stock represents an equity interest in the Federal Reserve Bank. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity).

+ References

+ Details

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