Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Dec. 31, 2022	Dec. 31, 2023
Statement of Cash Flows [Abstract]
Transfer from available for sale to held-to-maturity, fair value	$ 10,700	$ 10,691

Debt Securities, Held-To-Maturity, Fair Value, Transfer, Amount

No definition available.

Name:	zions_DebtSecuritiesHeldToMaturityFairValueTransferAmount
Namespace Prefix:	zions_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration