Unsecured Borrowings - Subordinated Borrowings (Parenthetical) (Detail) - Subordinated Debt [Member] - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Subordinated debt, par amount	$ 12,437	$ 14,136
Subordinated debt outstanding	15,571	18,529
Group Inc. [Member]
Debt Instrument [Line Items]
Subordinated debt, par amount	$ 12,440	$ 14,140

Face (par) amount of debt instrument at time of issuance.

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