Loans and Allowance for Credit Losses - Investments by Credit Quality (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	$ 33,410	$ 32,524
Financing receivable, held-for-sale	155	8
Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	28,922	27,196
Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	4,071	4,984
Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	251	180
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	166	164
Commercial and Financial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	30,728	29,970
Commercial and Financial | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	26,549	24,974
Commercial and Financial | Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	3,851	4,714
Commercial and Financial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	162	118
Commercial and Financial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	166	164
Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	2,682	2,554
Commercial Real Estate | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	2,373	2,222
Commercial Real Estate | Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	220	270
Commercial Real Estate | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	89	62
Commercial Real Estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	0	0
Geographic Distribution, Domestic | Commercial and Financial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	18,926	19,560
Geographic Distribution, Domestic | Commercial and Financial | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	16,127	16,024
Geographic Distribution, Domestic | Commercial and Financial | Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	2,509	3,278
Geographic Distribution, Domestic | Commercial and Financial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	162	118
Geographic Distribution, Domestic | Commercial and Financial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	128	140
Geographic Distribution, Domestic | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	2,682	2,554
Geographic Distribution, Domestic | Commercial Real Estate | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	2,373	2,222
Geographic Distribution, Domestic | Commercial Real Estate | Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	220	270
Geographic Distribution, Domestic | Commercial Real Estate | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	89	62
Geographic Distribution, Domestic | Loans to investment funds
Financing Receivable, Credit Quality Indicator [Line Items]
Overdrafts	4,830	$ 3,110
Geographic Distribution, Domestic | Loans to investment funds | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Overdrafts	4,470
Geographic Distribution, Domestic | Loans to investment funds | Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Overdrafts	356
Geographic Distribution, Domestic | Loans to investment funds | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Overdrafts	$ 2