| Consolidated Balance Sheets | |||||||||||||||||
| (dollars in millions) | |||||||||||||||||
| 12/31/2025 | 9/30/2025 | 12/31/2024 | |||||||||||||||
| Assets | |||||||||||||||||
| Loans | $ | 106,541 | $ | 105,902 | $ | 104,260 | |||||||||||
| Loans held for sale | 1,077 | 998 | 797 | ||||||||||||||
| Securities available for sale | 39,596 | 40,456 | 37,707 | ||||||||||||||
| Held-to-maturity securities | 8,622 | 7,509 | 7,395 | ||||||||||||||
| Trading account assets | 1,061 | 972 | 1,283 | ||||||||||||||
| Short-term investments | 10,163 | 13,334 | 17,504 | ||||||||||||||
| Other investments | 949 | 921 | 1,041 | ||||||||||||||
| Total earning assets | 168,009 | 170,092 | 169,987 | ||||||||||||||
| Allowance for loan and lease losses | (1,427) | (1,444) | (1,409) | ||||||||||||||
| Cash and due from banks | 1,287 | 1,938 | 1,743 | ||||||||||||||
| Premises and equipment | 628 | 606 | 614 | ||||||||||||||
| Goodwill | 2,752 | 2,752 | 2,752 | ||||||||||||||
| Other intangible assets | 8 | 13 | 27 | ||||||||||||||
| Corporate-owned life insurance | 4,432 | 4,428 | 4,394 | ||||||||||||||
| Accrued income and other assets | 8,481 | 8,803 | 8,797 | ||||||||||||||
| Discontinued assets | 211 | 221 | 263 | ||||||||||||||
| Total assets | $ | 184,381 | $ | 187,409 | $ | 187,168 | |||||||||||
| Liabilities | |||||||||||||||||
| Deposits in domestic offices: | |||||||||||||||||
| Interest-bearing deposits | 121,100 | 122,425 | 120,132 | ||||||||||||||
| Noninterest-bearing deposits | 27,613 | 28,340 | 29,628 | ||||||||||||||
| Total deposits | 148,713 | 150,765 | 149,760 | ||||||||||||||
| Federal funds purchased and securities sold under repurchase agreements | 13 | 10 | 14 | ||||||||||||||
| Bank notes and other short-term borrowings | 1,071 | 1,339 | 2,130 | ||||||||||||||
| Accrued expense and other liabilities | 4,286 | 4,276 | 4,983 | ||||||||||||||
| Long-term debt | 9,917 | 10,917 | 12,105 | ||||||||||||||
| Total liabilities | 164,000 | 167,307 | 168,992 | ||||||||||||||
| Equity | |||||||||||||||||
| Preferred stock | 2,500 | 2,500 | 2,500 | ||||||||||||||
| Common shares | 1,257 | 1,257 | 1,257 | ||||||||||||||
| Capital surplus | 6,035 | 6,002 | 6,038 | ||||||||||||||
| Retained earnings | 15,359 | 15,111 | 14,584 | ||||||||||||||
| Treasury stock, at cost | (2,810) | (2,619) | (2,733) | ||||||||||||||
| Accumulated other comprehensive income (loss) | (1,960) | (2,149) | (3,470) | ||||||||||||||
| Total equity | 20,381 | 20,102 | 18,176 | ||||||||||||||
| Total liabilities and equity | $ | 184,381 | $ | 187,409 | $ | 187,168 | |||||||||||
| Common shares outstanding (000) | 1,102,401 | 1,112,952 | 1,106,786 | ||||||||||||||
| Consolidated Statements of Income | ||||||||||||||||||||||||||
| (dollars in millions, except per share amounts) | ||||||||||||||||||||||||||
| Three months ended | Twelve months ended | |||||||||||||||||||||||||
| 12/31/2025 | 9/30/2025 | 12/31/2024 | 12/31/2025 | 12/31/2024 | ||||||||||||||||||||||
| Interest income | ||||||||||||||||||||||||||
| Loans | $ | 1,439 | $ | 1,466 | $ | 1,448 | $ | 5,749 | $ | 6,026 | ||||||||||||||||
| Loans held for sale | 18 | 18 | 20 | 61 | 60 | |||||||||||||||||||||
| Securities available for sale | 388 | 408 | 353 | 1,599 | 1,142 | |||||||||||||||||||||
| Held-to-maturity securities | 76 | 64 | 66 | 264 | 284 | |||||||||||||||||||||
| Trading account assets | 12 | 11 | 16 | 56 | 61 | |||||||||||||||||||||
| Short-term investments | 137 | 156 | 214 | 624 | 792 | |||||||||||||||||||||
| Other investments | 8 | 8 | 15 | 33 | 62 | |||||||||||||||||||||
| Total interest income | 2,078 | 2,131 | 2,132 | 8,386 | 8,427 | |||||||||||||||||||||
| Interest expense | ||||||||||||||||||||||||||
| Deposits | 688 | 748 | 821 | 2,919 | 3,307 | |||||||||||||||||||||
| Federal funds purchased and securities sold under repurchase agreements | 4 | 4 | 1 | 13 | 4 | |||||||||||||||||||||
| Bank notes and other short-term borrowings | 9 | 14 | 24 | 84 | 164 | |||||||||||||||||||||
| Long-term debt | 162 | 181 | 235 | 734 | 1,187 | |||||||||||||||||||||
| Total interest expense | 863 | 947 | 1,081 | 3,750 | 4,662 | |||||||||||||||||||||
| Net interest income | 1,215 | 1,184 | 1,051 | 4,636 | 3,765 | |||||||||||||||||||||
| Provision for credit losses | 108 | 107 | 39 | 471 | 335 | |||||||||||||||||||||
| Net interest income after provision for credit losses | 1,107 | 1,077 | 1,012 | 4,165 | 3,430 | |||||||||||||||||||||
| Noninterest income | ||||||||||||||||||||||||||
| Trust and investment services income | 156 | 150 | 142 | 591 | 557 | |||||||||||||||||||||
| Investment banking and debt placement fees | 243 | 184 | 221 | 780 | 688 | |||||||||||||||||||||
| Service charges on deposit accounts | 78 | 75 | 65 | 295 | 261 | |||||||||||||||||||||
| Operating lease income and other leasing gains | 9 | 11 | 15 | 43 | 76 | |||||||||||||||||||||
| Corporate services income | 81 | 72 | 69 | 294 | 275 | |||||||||||||||||||||
| Cards and payments income | 84 | 86 | 85 | 337 | 331 | |||||||||||||||||||||
| Corporate-owned life insurance income | 40 | 35 | 36 | 140 | 138 | |||||||||||||||||||||
| Consumer mortgage income | 16 | 14 | 16 | 58 | 58 | |||||||||||||||||||||
| Commercial mortgage servicing fees | 68 | 73 | 68 | 287 | 258 | |||||||||||||||||||||
| Other income | 7 | 8 | (5) | 23 | 23 | |||||||||||||||||||||
| Net securities gains (losses) | — | (6) | (908) | (6) | (1,856) | |||||||||||||||||||||
| Total noninterest income | 782 | 702 | (196) | 2,842 | 809 | |||||||||||||||||||||
| Noninterest expense | ||||||||||||||||||||||||||
| Personnel | 790 | 742 | 734 | 2,917 | 2,714 | |||||||||||||||||||||
| Net occupancy | 69 | 65 | 67 | 270 | 266 | |||||||||||||||||||||
| Computer processing | 106 | 105 | 107 | 425 | 414 | |||||||||||||||||||||
| Business services and professional fees | 61 | 44 | 55 | 193 | 174 | |||||||||||||||||||||
| Equipment | 22 | 20 | 20 | 83 | 80 | |||||||||||||||||||||
| Operating lease expense | 8 | 9 | 15 | 38 | 63 | |||||||||||||||||||||
| Marketing | 28 | 22 | 33 | 95 | 94 | |||||||||||||||||||||
| Intangible asset amortization | — | — | — | — | — | |||||||||||||||||||||
| Other expense | 157 | 170 | 198 | 682 | 740 | |||||||||||||||||||||
| Total noninterest expense | 1,241 | 1,177 | 1,229 | 4,703 | 4,545 | |||||||||||||||||||||
| Income (loss) from continuing operations before income taxes | 648 | 602 | (413) | 2,304 | (306) | |||||||||||||||||||||
| Income taxes | 139 | 112 | (169) | 476 | (143) | |||||||||||||||||||||
| Income (loss) from continuing operations | 509 | 490 | (244) | 1,828 | (163) | |||||||||||||||||||||
| Income (loss) from discontinued operations, net of taxes | 1 | (1) | — | 1 | 2 | |||||||||||||||||||||
| Net income (loss) | 510 | 489 | (244) | 1,829 | (161) | |||||||||||||||||||||
| Less: Net income (loss) attributable to noncontrolling interests | — | — | — | — | — | |||||||||||||||||||||
| Net income (loss) attributable to Key | $ | 510 | $ | 489 | $ | (244) | $ | 1,829 | $ | (161) | ||||||||||||||||
| Income (loss) from continuing operations attributable to Key common shareholders | $ | 474 | $ | 454 | $ | (279) | $ | 1,685 | $ | (306) | ||||||||||||||||
| Net income (loss) attributable to Key common shareholders | 475 | 453 | (279) | 1,686 | (304) | |||||||||||||||||||||
| Per common share | ||||||||||||||||||||||||||
| Income (loss) from continuing operations attributable to Key common shareholders | $ | .43 | $ | .41 | $ | (.28) | $ | 1.53 | $ | (.32) | ||||||||||||||||
| Income (loss) from discontinued operations, net of taxes | — | — | — | — | — | |||||||||||||||||||||
Net income (loss) attributable to Key common shareholders (a) | .43 | .41 | (.28) | 1.53 | (.32) | |||||||||||||||||||||
| Per common share — assuming dilution | ||||||||||||||||||||||||||
| Income (loss) from continuing operations attributable to Key common shareholders | $ | .43 | $ | .41 | $ | (.28) | $ | 1.52 | $ | (.32) | ||||||||||||||||
| Income (loss) from discontinued operations, net of taxes | — | — | — | — | — | |||||||||||||||||||||
Net income (loss) attributable to Key common shareholders (a) | .43 | .41 | $ | (.28) | 1.52 | (.32) | ||||||||||||||||||||
| Cash dividends declared per common share | $ | .205 | $ | .205 | $ | .205 | $ | .82 | $ | .82 | ||||||||||||||||
| Weighted-average common shares outstanding (000) | 1,095,171 | 1,100,830 | 986,829 | 1,098,558 | 949,561 | |||||||||||||||||||||
Effect of common share options and other stock awards (b) | 11,152 | 9,845 | — | 9,436 | — | |||||||||||||||||||||
Weighted-average common shares and potential common shares outstanding (000) (c) | 1,106,323 | 1,110,675 | 986,829 | 1,107,994 | 949,561 | |||||||||||||||||||||