Represents percentage of Allowance for credit losses to loans.

No definition available.

Name:	ncbs_PercentageOfAllowanceForCreditLossesToLoans
Namespace Prefix:	ncbs_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the percentage of loan under each category to total loan.

+ References

No definition available.

+ Details

Name:	ncbs_PercentageOfTotalNotesReceivableGross
Namespace Prefix:	ncbs_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount excluding accrued interest, of allowance for credit loss on financing receivable.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount excluding accrued interest, after allowance for credit loss, of financing receivable.

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount excluding accrued interest, before allowance for credit loss, of financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919230-210447

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 3B
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL120267963-210447

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_LoansAndLeasesReceivableDisclosureLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ncbs_RetailAndOtherFinancingReceivablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ncbs_CommercialAndIndustrialFinancingReceivablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ncbs_PaycheckProtectionProgramLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ncbs_CommercialRealEstateOwnerOccupiedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ncbs_AgriculturalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ncbs_ConstructionAndLandDevelopmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LienCategoryAxis=ncbs_FirstLienMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LienCategoryAxis=us-gaap_JuniorLienMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
Namespace Prefix:
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Period Type:

LOANS, ALLOWANCE FOR CREDIT LOSSES - LOANS, AND CREDIT QUALITY - Summary of loan composition (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 4,621,836	$ 2,789,101
Less ACL-Loans	49,672	32,173	$ 13,972	$ 13,153
Loans, net	$ 4,572,164	$ 2,756,928
ACL-Loans to loans (in percent)	1.07%	1.15%
% of Total	100.00%	100.00%
Retail & other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 50,807	$ 31,695
Less ACL-Loans	$ 932	$ 557	344
% of Total	1.00%	1.00%
Commercial Portfolio Segment \| Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 1,017,725	$ 750,718
Less ACL-Loans	$ 12,613	$ 11,644	5,471
% of Total	22.00%	27.00%
Commercial Portfolio Segment \| Paycheck Protection Program (“PPP”) loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 24,531	$ 186,016
% of Total	1.00%	7.00%
Commercial Portfolio Segment \| Owner-occupied commercial real estate (“CRE”)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 787,189	$ 521,300
Less ACL-Loans	$ 7,222	$ 5,872	3,010
% of Total	17.00%	19.00%
Commercial Portfolio Segment \| Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 794,728	$ 109,629
Less ACL-Loans	$ 9,547	$ 1,395	579
% of Total	17.00%	4.00%
Commercial Real Estate Portfolio Segment \| CRE investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 818,061	$ 460,721
Less ACL-Loans	$ 8,462	$ 5,441	1,600
% of Total	18.00%	16.00%
Commercial Real Estate Portfolio Segment \| Construction & land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 213,035	$ 131,283
Less ACL-Loans	$ 1,812	$ 984	414
% of Total	5.00%	5.00%
Residential \| Residential first mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 713,983	$ 444,155
Less ACL-Loans	$ 6,844	$ 4,773	1,669
% of Total	15.00%	16.00%
Residential \| Residential junior mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 131,424	$ 111,877
Less ACL-Loans	$ 1,340	$ 1,086	517
% of Total	3.00%	4.00%
Residential \| Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 70,353	$ 41,707
Less ACL-Loans	$ 900	$ 421	$ 368
% of Total	1.00%	1.00%