Short-Term Borrowings (Components of Other Short-Term Borrowings) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Short Term Debt
Securities sold under repurchase agreements	$ 469	$ 302
Derivative collateral	542	271
Total other short-term borrowings	$ 1,011	$ 573

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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant