Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Schedule of New Accounting Pronouncements and Changes in Accounting Principles

Accounting Guidance Adopted in 2025

Standard	Date of Adoption	Description	Effect on Financial Statements or Other Significant Matters
ASU 2023-09 Income Taxes (Topic 740)	Annual periods beginning January 1, 2025 Early adoption is permitted.	This guidance requires certain tax disclosures related to rate reconciliation and income taxes paid. The guidance should be applied on a prospective or retrospective basis.	The guidance did not have a material impact on Key’s disclosures. See Note 13 (“Income Taxes”) for enhanced disclosures.