| Total Revenues Net of Interest Expense After Provisions for Losses | $15.1B | $15.3B | $15.9B | $15.8B | $16.5B | $17.1B | $17.6B | $17.7B |
| Noninterest Expense | $11.3B | $12.1B | $13.1B | $12.5B | $12.9B | $13.3B | $14.5B | $13.9B |
| Revenue | $9.8B | $9.7B | — | $9.6B | $10.3B | $10.4B | — | $10.5B |
| Card Member rewards, business development and Card Member services | $6.8B | $6.8B | — | $7.2B | $7.5B | $7.7B | — | $8.5B |
| Interest and Dividend Income, Operating | $5.8B | $6.1B | $6.1B | $6.1B | $6.3B | $6.6B | $6.6B | $6.7B |
| Interest and Fee Income, Loans and Leases | $5.1B | $5.4B | $5.5B | $5.6B | $5.6B | $6.0B | $6.1B | $6.1B |
| Cash Provided by (Used in) Financing Activity, Including Discontinued Operation | — | $350.0M | — | $6.6B | $7.7B | — | — | $5.0B |
| Card Member Rewards | $4.2B | $4.2B | — | $4.4B | $4.6B | $4.6B | — | $4.9B |
| Interest Income (Expense), Operating | $3.7B | $4.0B | $4.0B | $4.2B | $4.2B | $4.5B | $4.5B | $4.7B |
| Salaries and employee benefits and other operating expenses | $3.0B | $3.8B | — | $3.8B | $3.8B | $4.0B | — | $3.9B |
| Cash Provided by (Used in) Operating Activity, Including Discontinued Operation | $4.5B | — | $5.8B | $4.8B | $4.4B | $6.2B | $3.1B | $3.8B |
| Debt issued (Note 13) | $5.5B | $4.6B | $83.0M | $4.8B | $11.1B | $6.5B | $2.0B | $3.5B |
| Reclassifications Net of Tax | $3.0B | $2.5B | — | $2.6B | $2.9B | $2.9B | — | $3.0B |
| Comprehensive Income (Loss), Net of Tax, Attributable to Parent | $3.0B | $2.5B | — | $2.6B | $3.0B | $2.9B | — | $2.9B |
| Other Comprehensive Income (Loss) | $3.0B | $2.5B | — | $2.6B | $3.0B | $2.9B | — | $2.9B |
| Cash Provided by (Used in) Investing Activity, Including Discontinued Operation | -$5.5B | -$3.5B | -$12.2B | $451.0M | -$6.8B | -$6.6B | -$9.9B | -$2.9B |
| Payments to Acquire Investments | $355.0M | $448.0M | $383.0M | $239.0M | $530.0M | $545.0M | $446.0M | $2.0B |
| Card Member Services | $1.2B | $1.2B | — | $1.3B | $1.3B | $1.5B | — | $2.0B |
| Payments for Repurchase of Common Stock | $1.8B | $1.9B | $1.0B | $1.2B | $1.4B | $2.4B | $899.0M | $1.9B |
| Treasury stock, value, acquired | $1.8B | $1.9B | — | $678.0M | $1.4B | $2.3B | — | $1.7B |
| Business development | $1.4B | $1.4B | $1.6B | $1.5B | $1.6B | $1.6B | $1.7B | $1.6B |
| Repayments of Long-Term Debt | $2.9B | $3.2B | $3.4B | $3.5B | $4.4B | $7.0B | $3.3B | $1.5B |
| Marketing | $1.5B | $1.5B | $1.6B | $1.5B | $1.6B | $1.6B | $1.6B | $1.5B |
| Increase (Decrease) in Other Operating Assets | — | $285.0M | -$1.2B | -$18.0M | $1.2B | $181.0M | $1.4B | $1.4B |
| Interest Expense, Deposits | $1.4B | $1.4B | $1.4B | $1.3B | $1.4B | $1.4B | $1.3B | $1.3B |
| Total provisions for credit losses | $1.3B | $1.4B | $1.3B | $1.2B | $1.4B | $1.3B | $1.4B | $1.3B |
| Capital Expenditures | $565.0M | $455.0M | $495.0M | $430.0M | $619.0M | $654.0M | $722.0M | $1.1B |
| Payments to Acquire Property, Plant, and Equipment | $565.0M | $455.0M | $495.0M | $430.0M | $619.0M | $654.0M | $722.0M | $1.1B |
| Account Balances | $971.0M | $956.0M | — | $1.0B | $946.0M | $1.0B | — | $1.1B |
| Data processing and equipment | — | — | — | $705.0M | — | — | — | $767.0M |
| Interest Expense, Long-Term Debt | $639.0M | $697.0M | $642.0M | $629.0M | $703.0M | $760.0M | $717.0M | $686.0M |
| Dividends, Common Stock, Cash | $503.0M | $494.0M | — | $576.0M | $576.0M | $567.0M | — | $652.0M |
| Payments of Dividends | $521.0M | $516.0M | $510.0M | $509.0M | $593.0M | $586.0M | $583.0M | $583.0M |
| Interest Income, Deposits with Financial Institutions | $677.0M | $689.0M | $556.0M | $569.0M | $599.0M | $632.0M | $501.0M | $512.0M |
| Payments for (Proceeds from) Loans Receivable | $6.4B | $2.9B | $11.3B | -$835.0M | $5.3B | $5.7B | $9.4B | -$512.0M |
| Payments to Acquire Businesses, Net of Cash Acquired | — | $90.0M | $364.0M | $0.0 | $633.0M | — | — | $498.0M |
| Increase (Decrease) in Accounts Payable and Other Operating Liabilities | $701.0M | -$5.9B | — | $228.0M | $1.2B | $1.9B | — | $476.0M |
| Depreciation, Amortization and Accretion, Net | $421.0M | $437.0M | $428.0M | $433.0M | $427.0M | $455.0M | $462.0M | $468.0M |
| Lease obligation incurred | — | — | — | — | — | — | — | $370.0M |
| Contribution of property | — | — | — | — | — | — | — | $370.0M |
| Other Noncash Income (Expense) | $535.0M | — | $231.0M | -$213.0M | $152.0M | -$13.0M | $311.0M | $282.0M |
| Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-Sale | $1.3B | $341.0M | $304.0M | $285.0M | $302.0M | $289.0M | $577.0M | $233.0M |
| Stock-based compensation | $104.0M | $113.0M | $111.0M | $158.0M | $127.0M | $125.0M | $141.0M | $203.0M |
| Other Net Expenses | $326.0M | $476.0M | — | $400.0M | $375.0M | $406.0M | — | $147.0M |
| Deferred taxes | — | -$473.0M | -$73.0M | -$20.0M | -$365.0M | -$257.0M | — | $145.0M |
| Proceeds from (Repayments of) Short-Term Debt | — | — | $38.0M | $131.0M | — | — | -$28.0M | $110.0M |
| Account balance, modified and subsequent default | $74.0M | $95.0M | — | $84.0M | $83.0M | $74.0M | — | $89.0M |
| Stockholders' Equity, Other | -$91.0M | -$83.0M | — | $407.0M | -$93.0M | -$124.0M | — | $86.0M |
| Income tax credits and Other income tax benefits recognized in tax provision | $56.0M | $51.0M | — | $66.0M | $73.0M | $65.0M | — | $76.0M |
| Investment Program, Proportional Amortization Method, Applied, Amortization Expense | $48.0M | $48.0M | — | $57.0M | $58.0M | $60.0M | — | $66.0M |
| Payment for Origination and Purchase, Loan, Held-for-Sale | $0.0 | $0.0 | $0.0 | $0.0 | — | — | — | $42.0M |
| Other Comprehensive Income (Loss), Net of Tax | -$45.0M | $5.0M | — | $29.0M | $118.0M | -$1.0M | — | -$34.0M |
| OCI Attributable to Parent | -$45.0M | $5.0M | — | $29.0M | $118.0M | -$1.0M | — | -$34.0M |
| Other comprehensive income/(loss) | -$45.0M | $5.0M | — | $29.0M | $118.0M | -$1.0M | — | -$34.0M |
| Other Comprehensive Income (Loss), Net of Tax, Attributable to Parent | -$45.0M | $5.0M | — | $29.0M | $118.0M | -$1.0M | — | -$34.0M |
| OCI Net of Tax, Parent | -$45.0M | $5.0M | — | $29.0M | $118.0M | -$1.0M | — | -$34.0M |
| Debt And Equity Securities, Unrealized Loss | — | — | $4.0M | $17.0M | — | — | — | $24.0M |
| Foreign Currency Translation Adjustments | -$49.0M | $1.0M | — | $17.0M | $115.0M | -$6.0M | — | -$22.0M |
| Change in foreign currency translation | -$49.0M | $1.0M | — | $17.0M | $115.0M | -$6.0M | — | -$22.0M |
| Foreign Currency Translation Adjustments, Net of Tax | -$49.0M | $1.0M | — | $17.0M | $115.0M | -$6.0M | — | -$22.0M |
| OCI - Foreign Currency Translation Adjustment | -$49.0M | $1.0M | — | $17.0M | $115.0M | -$6.0M | — | -$22.0M |
| Foreign currency translation | -$49.0M | $1.0M | — | $17.0M | $115.0M | -$6.0M | — | -$22.0M |
| Currency Translation Adjustment, Net of Tax | -$49.0M | $1.0M | — | $17.0M | $115.0M | -$6.0M | — | -$22.0M |
| OCI Foreign Currency Translation | -$49.0M | $1.0M | — | $17.0M | $115.0M | -$6.0M | — | -$22.0M |
| Earnings allocated to participating share awards | $23.0M | $18.0M | — | $18.0M | $18.0M | $20.0M | — | $19.0M |
| Interest and Dividend Income, Securities, Operating | $25.0M | $18.0M | $18.0M | $14.0M | $17.0M | $15.0M | $17.0M | $17.0M |
| Net increase (decrease) in interest expense on long term debt and other | $69.0M | $82.0M | — | $12.0M | $29.0M | $47.0M | — | -$16.0M |
| Dividends on preferred shares | $15.0M | $15.0M | — | $14.0M | $15.0M | $14.0M | — | $14.0M |
| Equity Securities, FV-NI, Unrealized Loss | — | — | $2.0M | $8.0M | — | — | — | $9.0M |
| Sale of investments | $29.0M | $4.0M | $7.0M | $0.0 | $1.0M | $41.0M | $5.0M | $8.0M |
| OCI Available-for-Sale Securities Adjustment | $3.0M | $4.0M | — | $3.0M | $0.0 | $1.0M | — | -$7.0M |
| OCI - Available-for-Sale Securities Adjustment | $3.0M | $4.0M | — | $3.0M | $0.0 | $1.0M | — | -$7.0M |
| Proceeds from Issuance of Common Stock | $17.0M | $3.0M | $51.0M | $22.0M | $0.0 | $26.0M | $9.0M | $7.0M |
| OCI Defined Benefit Plans Adjustment (Net of Tax) Parent | -$1.0M | $0.0 | — | -$9.0M | -$3.0M | -$4.0M | — | $5.0M |
| Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent | -$1.0M | $0.0 | — | -$9.0M | -$3.0M | -$4.0M | — | $5.0M |
| Debt And Equity Securities, Unrealized Gain | -$17.0M | $2.0M | $3.0M | $2.0M | — | $1.0M | — | $2.0M |
| Tax expense (benefit) | $8.0M | -$33.0M | — | -$61.0M | -$143.0M | -$8.0M | — | $2.0M |
| Other Comprehensive Income Tax | $8.0M | -$33.0M | — | -$61.0M | -$143.0M | -$8.0M | — | $2.0M |
| Other Comprehensive Income (Loss), Tax | $8.0M | -$33.0M | — | -$61.0M | -$143.0M | -$8.0M | — | $2.0M |
| Common Stock Dividends Per Share Declared | $0.7 | $0.7 | — | $0.8 | $0.8 | $0.8 | — | $1.0 |
| Common Stock Dividends Per Share | $0.7 | $0.7 | — | $0.8 | $0.8 | $0.8 | — | $1.0 |
| Dividends per share declared | $0.7 | $0.7 | — | $0.8 | $0.8 | $0.8 | — | $1.0 |
| Dividends per share declared | $0.7 | $0.7 | — | $0.8 | $0.8 | $0.8 | — | $1.0 |
| Common Stock Dividends Per Share Declared | $0.7 | $0.7 | — | $0.8 | $0.8 | $0.8 | — | $1.0 |
| Dividends declared (in dollars per share) | $0.7 | $0.7 | — | $0.8 | $0.8 | $0.8 | — | $1.0 |
| Common Stock Dividends Per Share Declared | $0.7 | $0.7 | — | $0.8 | $0.8 | $0.8 | — | $1.0 |
| Common Stock Dividends Per Share Declared | $0.7 | $0.7 | — | $0.8 | $0.8 | $0.8 | — | $1.0 |
| Effective tax rates | $0.2 | $0.2 | — | $0.2 | $0.2 | $0.2 | — | $0.2 |
| Gross Unrealized Gains | -$17.0M | $0.0 | $4.0M | $1.0M | -$1.0M | $0.0 | $0.0 | $0.0 |
| Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent | $0.0 | $0.0 | — | $0.0 | $0.0 | $0.0 | — | $0.0 |
| Reclassification from AOCI, Net of Tax | $0.0 | $0.0 | — | $0.0 | $0.0 | $0.0 | — | $0.0 |
