Cash and Cash Equivalents - Summary of Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Abstract]
Cash and due from banks	$ 15,237,612	$ 6,492,443
Securities purchased under agreements to resell	450,164	289,340
Total cash and cash equivalents	$ 15,687,776	$ 6,781,783

Amount, after the effects of master netting arrangements, of funds outstanding loaned in the form of a security resale agreement between the entity and another party for the purchase and resale of identical or substantially the same securities at a date certain for a specified price. Includes purchases of participations in pools of securities that are subject to a resale agreement, assets not subject to a master netting arrangement and not elected to be offset.

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Name:	us-gaap_SecuritiesPurchasedUnderAgreementsToResell
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant