| Interest-Bearing Deposit Liabilities, Domestic | $125.7B | $129.3B | $133.1B | $135.1B | $134.7B | $136.6B | $144.4B | $182.6B |
| FHLB borrowings and advances, collateral | $101.2B | $102.2B | $105.4B | $107.4B | $108.3B | $107.3B | $114.2B | $141.2B |
| Aggregate Notional Principal Outstanding | $44.5B | $43.8B | $45.8B | $48.6B | $46.2B | $42.3B | $44B | $45.1B |
| Derivative Notional Amount | $44.5B | $43.8B | $45.8B | $48.6B | $46.2B | $42.3B | $44B | $45.1B |
| Notional | $44.5B | $43.8B | $45.8B | $48.6B | $46.2B | $42.3B | $44B | $45.1B |
| Cost or Amortized Cost | $31B | $31.2B | $30.7B | $30.9B | $31.1B | $28.6B | $28.5B | $38.1B |
| Estimated Fair Value | $27.5B | $28.5B | $27.3B | $27.8B | $28.3B | $26.1B | $26.1B | $35.6B |
| Debt Securities, Available-for-Sale, Unrealized Loss Position | $23.8B | $21.7B | $22.8B | $22.3B | $22.1B | $18.6B | $17.7B | $27B |
| Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 | $19.4B | $19.1B | $19.3B | $19.4B | $19.6B | $19B | $19.7B | $24.1B |
| Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 | $16.1B | $16.6B | $16.1B | $16.6B | $17B | $16.6B | $17.4B | $21.8B |
| 12 months or more | $19.7B | $20.3B | $18B | $18B | $16.8B | $17.4B | $16.5B | $15.9B |
| Held-to-maturity securities, fair value | $15B | $15.7B | $16.4B | $16.3B | $16B | $15.6B | $15.3B | $14.8B |
| After 10 years | $14.9B | $14.6B | $14.2B | $13.9B | $13.5B | $13.1B | $12.7B | $12.5B |
| Less than 12 months | $4.1B | $1.4B | $4.7B | $4.2B | $5.3B | $1.2B | $1.2B | $11.1B |
| HTM unrealized loss position 12 months or more - fair value | $12.2B | $12.3B | $11.5B | $11.5B | $11.2B | $11.4B | $11.1B | $10.4B |
| Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year One Through Five | $3.8B | $4.8B | $6B | $6.7B | $5.9B | $5.6B | $5.6B | $6.6B |
| Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five | $3.6B | $4.7B | $5.8B | $6.6B | $5.9B | $5.6B | $5.6B | $6.6B |
| Sales-Type and Direct Financing Leases, Payment to be Received | $5B | $5.1B | — | $5.2B | $5.2B | $5.2B | — | $5.4B |
| Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year One | $5.5B | $4.9B | $3.6B | $3.1B | $3.8B | $2.1B | $1.4B | $5.1B |
| Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One | $5.5B | $4.9B | $3.6B | $3.1B | $3.8B | $2.1B | $1.4B | $5.1B |
| Time deposit accounts (including certificates of deposits) in denominations that met or exceeded the insured limit | $1.4B | $1.5B | $1.5B | $1.4B | $1.3B | $1.3B | $2.1B | $4.2B |
| ACL balance, end of period | $2.4B | $2.4B | — | $2.5B | $2.5B | $2.6B | — | $3.4B |
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax | $3.6B | $2.8B | $3.5B | $3.1B | $2.8B | $2.6B | $2.4B | $2.5B |
| Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss | $3.6B | $2.8B | $3.5B | $3.1B | $2.8B | $2.6B | $2.4B | $2.5B |
| Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | $3.6B | $2.8B | $3.4B | $3B | $2.8B | $2.6B | $2.4B | $2.5B |
| Common stock, shares authorized (in shares) | $2.3B | $2.3B | $2.3B | $2.3B | $2.3B | $2.3B | $2.3B | $2.3B |
| Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 | $2.4B | $2.4B | $1.9B | $1.7B | $1.8B | $1.9B | $1.9B | $2.2B |
| Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 | $2.2B | $2.3B | $1.7B | $1.6B | $1.7B | $1.8B | $1.8B | $2.1B |
| Common stock, shares issued (in shares) | — | — | $1.5B | — | — | — | $1.6B | $2B |
| Common Stock, Shares, Outstanding | $1.5B | $1.5B | $1.5B | $1.5B | $1.5B | $1.5B | $1.6B | $2B |
| Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss | $2.3B | $1.8B | $2.3B | $2B | $1.9B | $1.7B | $1.6B | $1.7B |
| Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss | $2.3B | $1.8B | $2.3B | $2B | $1.9B | $1.7B | $1.6B | $1.7B |
| 1-5 years | $38M | $784M | $1.8B | $2.1B | $2.1B | $2B | $1.8B | $1.7B |
| Financing Receivable, Unamortized Loan Cost (Fee) and Purchase Premium (Discount) | $354M | -$348M | -$468M | -$509M | -$503M | -$638M | $815M | $1.5B |
| Fair value of long-term debt | $480M | $416M | $821M | $1.1B | $1B | $1.3B | $1.2B | $1.4B |
| Long-term debt, gross | — | — | — | — | — | — | $1.2B | $1.4B |
| Gross Carrying Amount | — | — | — | — | — | — | $539M | $1.4B |
| Cumulative Cost Basis | $843M | $826M | $822M | $880M | $878M | $870M | $994M | $1.3B |
| Cost | $843M | $826M | $822M | $880M | $878M | $870M | $994M | $1.3B |
| 2028 | $895M | $775M | — | $988M | $961M | $934M | — | $1.1B |
| 2029 | $855M | $781M | — | $972M | $947M | $927M | — | $1B |
| 2027 | $557M | $818M | — | $700M | $656M | $601M | — | $975M |
| 2030 | $865M | $813M | — | $992M | $975M | $956M | — | $919M |
| Fair Value Measurement Disclosure | $1.6B | $884M | $668M | $598M | $609M | $508M | $519M | $572M |
| Derivatives, gross, liabilities | $1.6B | $884M | $668M | $598M | $609M | $508M | $519M | $572M |
| Loans modified after 12 months | $753M | $772M | — | $855M | $871M | $751M | — | $568M |
| Derivative, gross, assets | $1.6B | $1.4B | $610M | $507M | $568M | $502M | $507M | $561M |
| Within 1 year | $0 | $245M | $255M | $201M | $255M | $404M | $603M | $502M |
| Finite-Lived Intangible Assets, Accumulated Amortization | — | — | — | — | — | — | $394M | $435M |
| With an allowance | $175M | $224M | $239M | $220M | $241M | $234M | $282M | $421M |
| Gross Assets/Liabilities | $720M | $392M | $578M | $453M | $386M | $345M | $350M | $397M |
| Derivative Liability | $720M | $392M | $578M | $453M | $386M | $345M | $350M | $397M |
| Collateral already posted, aggregate fair value | $104M | $172M | — | $207M | $207M | $111M | — | $379M |
| Guarantor Obligations - Maximum Exposure | $117M | $201M | $201M | $201M | $201M | $281M | $366M | $366M |
| Indemnification Liability Maximum Exposure | $117M | $201M | $201M | $201M | $201M | $281M | $366M | $366M |
| Value of financial guarantee (up to) | $117M | $201M | $201M | $201M | $201M | $281M | $366M | $366M |
| Derivative Asset, Subject to Master Netting Arrangement, Gross Liability and Collateral, Obligation to Return Cash, Offset | $1.2B | $888M | $344M | $359M | $354M | $291M | $260M | $295M |
| Securities Collateral Held /Pledged Under Master Netting Agreements | $21M | $70M | $67M | $67M | $66M | $65M | $120M | $286M |
| Investment securities and cash collateral pledged to company | $436M | $446M | — | $239M | $175M | $150M | — | $212M |
| Assets held in trust for deferred compensation plans | — | — | — | — | — | — | $216M | $212M |
| Hedged Asset (Statement of Financial Position) | $642M | $377M | $458M | $336M | $197M | $160M | $177M | $196M |
| Derivative Asset, Including Not Subject to Master Netting Arrangement, after Offset and Deduction | $397M | $456M | $226M | $128M | $188M | $184M | $145M | $186M |
| Derivative netting, Liabilities | $884M | $492M | $90M | $145M | $223M | $163M | $169M | $175M |
| Loans Receivable Fair Value Disclosure | $175M | $175M | $173M | $175M | $172M | $171M | $167M | $166M |
| Nonperforming Loans and Leases Percentage | $137M | $125M | $146M | $126M | $122M | $81M | $166M | $156M |
| 5-10 years | $64M | $63M | $65M | $67M | $59M | $146M | $144M | $136M |
| Credit risks from interest rate swaps used for trading purposes | $64M | $141M | $76M | $77M | $142M | $158M | $168M | $125M |
| Off-Balance-Sheet, Credit Loss, Liability | $119M | $201M | $202M | $215M | $184M | $188M | $206M | $125M |
| Aggregate credit risk, net of collateral | $351M | $319M | $192M | $61M | $41M | $28M | $73M | $91M |
| Other securities | — | — | — | — | — | — | $42M | $64M |
| Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | $35M | $9M | $74M | $42M | $35M | $13M | $14M | $53M |
| Noncontrolling interests in subsidiaries | $48M | $46M | $42M | $52M | $42M | $38M | $37M | $46M |
| Accrued Interest, held-to-maturity | $34M | $38M | $46M | $43M | $46M | $41M | $44M | $39M |
| Fair value hedging adjustments | — | — | -$56M | — | -$49M | -$46M | -$42M | -$39M |
| Derivative Liability, Including Not Subject to Master Netting Arrangement, after Offset and Deduction | $616M | $240M | $195M | $251M | $200M | $240M | $215M | $34M |
| Gross Unrealized Gains | $92M | $95M | $13M | $32M | $44M | $58M | $66M | $26M |
| Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain | $1M | $14M | $3M | $16M | $24M | $20M | $25M | $10M |
| Treasury stock, shares (in shares) | $7.3M | $7.2M | $7M | $7.2M | $7M | $6.9M | $7.2M | $7.3M |
| Securities Collateral Held /Pledged Under Master Netting Agreements | $0 | $0 | $5M | $11M | $4M | $2M | $2M | $7M |
| Preferred Stock, Shares Authorized | $6.6M | $6.6M | $6.6M | $6.6M | $6.6M | $6.6M | $6.6M | $6.6M |
| Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs | $1M | -$9M | $2M | $3M | $7M | $3M | $3M | $6M |
| Preferred Stock, Shares Outstanding | $881.6K | $881.6K | $877.5K | $877.5K | $877.5K | $885K | $885K | $891.9K |
| Common stock, par value (in dollars per share) | $0 | $0 | $0 | $0 | $0 | $0 | $0 | $0 |
| Available-for-sale securities, allowance for credit loss | — | — | $0 | $0 | $0 | $0 | $0 | $0 |
| Debt securities, held-to-maturity, allowance for credit loss (less than) | — | — | $0 | $0 | $0 | $0 | $0 | $0 |
| Unrealized Gross Gains | $1M | $0 | $1M | $0 | $0 | $0 | $0 | $0 |
| Equity Securities, FV-NI, Accumulated Gross Unrealized Loss, Before Tax | — | — | — | — | — | — | $0 | $0 |
| Carrying value of assets pledged as collateral against repurchase agreements | $156M | $189M | $224M | $201M | $219M | $205M | $40M | $0 |
