Short-Term Borrowings - Summary of Short-Term Borrowings (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Securities sold under repurchase agreements	$ 251	$ 256
Federal Home Loan Bank advances	2,230	2,285
Federal funds purchased	1,535	1,000
Subordinated notes	113	138
Total short-term borrowings	$ 4,129	$ 3,679
Short-term advances, overnight maturities	57.20%	75.70%

Short-term Advances, Overnight Maturities

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Amount of short-term subordinated notes with no maturity date or original maturities of less than one year.

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Amount of short term borrowing where a bank borrows, at the federal funds rate, from another bank.

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Amount of advances from Federal Home Loan Bank (FHLBank) maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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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.

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Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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