Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies (Details Textual)

v2.4.1.9
Summary of Significant Accounting Policies (Details Textual) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Business Acquisition [Line Items]    
Goodwill $ 1,611,000us-gaap_Goodwill $ 0us-gaap_Goodwill
Loans Receivable, Fair Value Disclosure 480,736,000us-gaap_LoansReceivableFairValueDisclosure 427,719,000us-gaap_LoansReceivableFairValueDisclosure
Amortization of Intangible Assets 9,000us-gaap_AmortizationOfIntangibleAssets  
First Federal Acquisition [Member]    
Business Acquisition [Line Items]    
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities 39,600,000us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities
/ us-gaap_BusinessAcquisitionAxis
= nwin_FirstFederalAcquisitionMember
 
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Marketable Securities 3,800,000us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsMarketableSecurities
/ us-gaap_BusinessAcquisitionAxis
= nwin_FirstFederalAcquisitionMember
 
Business Combination, Acquired Receivables, Fair Value 29,100,000us-gaap_BusinessCombinationAcquiredReceivablesFairValue
/ us-gaap_BusinessAcquisitionAxis
= nwin_FirstFederalAcquisitionMember
 
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment 967,000us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment
/ us-gaap_BusinessAcquisitionAxis
= nwin_FirstFederalAcquisitionMember
 
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Land 690,000us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLand
/ us-gaap_BusinessAcquisitionAxis
= nwin_FirstFederalAcquisitionMember
 
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets 37,900,000us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets
/ us-gaap_BusinessAcquisitionAxis
= nwin_FirstFederalAcquisitionMember
 
Goodwill 1,600,000us-gaap_Goodwill
/ us-gaap_BusinessAcquisitionAxis
= nwin_FirstFederalAcquisitionMember
 
Finite-lived Intangible Assets Acquired 93,000us-gaap_FinitelivedIntangibleAssetsAcquired1
/ us-gaap_BusinessAcquisitionAxis
= nwin_FirstFederalAcquisitionMember
 
Federal Reserve Bank [Member]    
Business Acquisition [Line Items]    
Cash 827,000us-gaap_Cash
/ nwin_BankingAxis
= nwin_FederalReserveBankMember
656,000us-gaap_Cash
/ nwin_BankingAxis
= nwin_FederalReserveBankMember
Premises And Equipment [Member] | Minimum [Member]    
Business Acquisition [Line Items]    
Property, Plant and Equipment, Useful Life 26 years  
Premises And Equipment [Member] | Maximum [Member]    
Business Acquisition [Line Items]    
Property, Plant and Equipment, Useful Life 39 years  
Furniture and Equipment [Member] | Minimum [Member]    
Business Acquisition [Line Items]    
Property, Plant and Equipment, Useful Life 2 years  
Furniture and Equipment [Member] | Maximum [Member]    
Business Acquisition [Line Items]    
Property, Plant and Equipment, Useful Life 10 years  
Core Deposits [Member]    
Business Acquisition [Line Items]    
Finite-Lived Intangible Asset, Useful Life 7 years 10 months 24 days  
Finite-Lived Intangible Assets, Amortization Method straight line basis  
Core Deposits [Member] | First Federal Acquisition [Member]    
Business Acquisition [Line Items]    
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities 7,200,000us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities
/ us-gaap_BusinessAcquisitionAxis
= nwin_FirstFederalAcquisitionMember
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_CoreDepositsMember
 
Certificates of Deposit [Member]    
Business Acquisition [Line Items]    
Finite-Lived Intangible Asset, Useful Life 17 months  
Amortization of Intangible Assets 126,000us-gaap_AmortizationOfIntangibleAssets
/ us-gaap_CashAndCashEquivalentsAxis
= us-gaap_CertificatesOfDepositMember
 
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months 150,000us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths
/ us-gaap_CashAndCashEquivalentsAxis
= us-gaap_CertificatesOfDepositMember
 
Deposits, Fair Value Disclosure 276,000us-gaap_DepositsFairValueDisclosure
/ us-gaap_CashAndCashEquivalentsAxis
= us-gaap_CertificatesOfDepositMember
 
Finite-Lived Intangible Assets, Amortization Method straight line basis  
Certificates of Deposit [Member] | First Federal Acquisition [Member]    
Business Acquisition [Line Items]    
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities 29,800,000us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities
/ us-gaap_BusinessAcquisitionAxis
= nwin_FirstFederalAcquisitionMember
/ us-gaap_CashAndCashEquivalentsAxis
= us-gaap_CertificatesOfDepositMember
 
Home Equity Line of Credit [Member]    
Business Acquisition [Line Items]    
Loans Receivable, Fair Value Disclosure 1,100,000us-gaap_LoansReceivableFairValueDisclosure
/ us-gaap_FinancialInstrumentAxis
= us-gaap_HomeEquityMember
 
Finite-Lived Intangible Asset, Useful Life 55 months  
Finite-Lived Intangible Assets, Amortization Method straight line basis  
Home Equity Line of Credit [Member] | Loans Receivable [Member]    
Business Acquisition [Line Items]    
Amortization of Intangible Assets 318,000us-gaap_AmortizationOfIntangibleAssets
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= us-gaap_LoansReceivableMember
/ us-gaap_FinancialInstrumentAxis
= us-gaap_HomeEquityMember
 
Finite-Lived Intangible Assets, Amortization Expense, Year Three 206,000us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= us-gaap_LoansReceivableMember
/ us-gaap_FinancialInstrumentAxis
= us-gaap_HomeEquityMember
 
Finite-Lived Intangible Assets, Amortization Expense, Year Four $ 171,000us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= us-gaap_LoansReceivableMember
/ us-gaap_FinancialInstrumentAxis
= us-gaap_HomeEquityMember