Loans, Lending Commitments and Related Allowance for Credit Losses - Past Due Loans Held for Investment before Allowance (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 182,926	$ 174,956
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	47,236	44,251
Residential real estate \| Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 191	$ 209

Amount excluding accrued interest, before allowance for credit loss, of financing receivable.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919230-210447

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 3B
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL120267963-210447

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