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Amount, before allowance and fees, of loans and leases receivable. Excludes loans and leases covered under loss sharing agreements.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Amount, after allowance for bad debt, of loan receivables held-for-sale that are not part of a disposal group. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

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Commercial lending loans - owner occupied

No definition available.

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Balance Type:	debit
Period Type:	instant

Commercial real estate term loans

No definition available.

Name:	zions_CommercialRealEstateTermLoans
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Land Development Loans, Loans receivable commercial construction and land development

No definition available.

Name:	zions_LandDevelopmentLoansLoansReceivableCommercialConstructionandLandDevelopment
Namespace Prefix:	zions_
Data Type:	xbrli:monetaryItemType
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Loan Credit Quality Outstanding, Leasing

No definition available.

Name:	zions_LoanCreditQualityOutstandingLeasing
Namespace Prefix:	zions_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Loans Credit Quality Outstanding, 1-4 Family Residential

No definition available.

Name:	zions_LoansCreditQualityOutstanding14FamilyResidential
Namespace Prefix:	zions_
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Balance Type:	credit
Period Type:	instant

Loans Credit Quality Outstanding, Bankcard

No definition available.

Name:	zions_LoansCreditQualityOutstandingBankcard
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Loans Credit Quality Outstanding, Commercial Real Estate

No definition available.

Name:	zions_LoansCreditQualityOutstandingCommercialRealEstate
Namespace Prefix:	zions_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Loans Credit Quality Outstanding, Construction and Other

No definition available.

Name:	zions_LoansCreditQualityOutstandingConstructionandOther
Namespace Prefix:	zions_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Loans Credit Quality Outstanding, Home Equity Credit Line

No definition available.

Name:	zions_LoansCreditQualityOutstandingHomeEquityCreditLine
Namespace Prefix:	zions_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Loans Credit Quality Outstanding, Municipal

No definition available.

Name:	zions_LoansCreditQualityOutstandingMunicipal
Namespace Prefix:	zions_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Loans Credit Quality Outstanding, Other

No definition available.

Name:	zions_LoansCreditQualityOutstandingOther
Namespace Prefix:	zions_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Loans Credit Quality Outstanding, PPP

No definition available.

Name:	zions_LoansCreditQualityOutstandingPPP
Namespace Prefix:	zions_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Term Loans Credit Quality Outstanding, Commercial And Industrial, Amortized Cost Basis, Originated in Current Fiscal Year

No definition available.