$NFBK
Northfield Bancorp, Inc. Stock $nfbk

$nfbk Overview Financials Valuation SEC Filings Company Website

2021 Q2 Form 10-Q Financial Statement

#000149322521000098 Filed on August 09, 2021

Income Statement

Concept	2021 Q2	2020 Q2	2020 Q1
Revenue	$43.24M	$40.91M	$42.73M
YoY Change	5.68%	1.79%	8.28%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$1.030M	$860.0K	$860.0K
YoY Change	19.77%	2.38%	2.38%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense	$4.549M	$10.68M	$12.80M
YoY Change	-57.41%	-18.05%	5.46%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$27.43M	$14.69M	$6.176M
YoY Change	86.72%	40.14%	-45.73%
Income Tax	$7.639M	$3.899M	$1.625M
% Of Pretax Income	27.85%	26.54%	26.31%
Net Earnings	$19.79M	$10.79M	$4.551M
YoY Change	83.4%	31.56%	-48.11%
Net Earnings / Revenue	45.78%	26.38%	10.65%
Basic Earnings Per Share	$0.40	$0.23	$0.10
Diluted Earnings Per Share	$0.40	$0.23	$0.10
COMMON SHARES
Basic Shares Outstanding	48.91M shares	46.84M shares	46.79M shares
Diluted Shares Outstanding	49.31M shares	46.87M shares	46.98M shares

Balance Sheet

Concept	2021 Q2	2020 Q2	2020 Q1
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$193.2M	$110.9M	$114.7M
Short-Term Investments
Other Short-Term Assets
YoY Change
Inventory
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets
YoY Change
LONG-TERM ASSETS
Property, Plant & Equipment	$27.27M	$25.27M	$25.67M
YoY Change	7.91%	-1.67%	1.82%
Goodwill	$41.01M	$38.41M	$38.41M
YoY Change	6.77%	0.0%	0.0%
Intangibles
YoY Change
Long-Term Investments
YoY Change
Other Assets
YoY Change
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$5.427B	$5.042B	$4.997B
YoY Change	7.64%	5.73%	9.69%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$24.20M	$19.90M	$22.40M
YoY Change	21.61%	-4.33%	8.21%
Accrued Expenses	$70.90M	$71.20M	$70.10M
YoY Change	-0.42%	0.14%	-0.99%
Deferred Revenue
YoY Change
Short-Term Debt	$50.00M	$75.00M	$75.00M
YoY Change	-33.33%	0.0%
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$95.10M	$91.10M	$92.50M
YoY Change	4.39%	-0.87%	1.09%
LONG-TERM LIABILITIES
Long-Term Debt	$420.3M	$541.3M	$641.4M
YoY Change	-22.35%	-12.71%	56.74%
Other Long-Term Liabilities
YoY Change
Total Long-Term Liabilities	$420.3M	$541.3M	$641.4M
YoY Change	-22.35%	-12.71%	56.74%
TOTAL LIABILITIES
Total Short-Term Liabilities	$95.10M	$91.10M	$92.50M
Total Long-Term Liabilities	$420.3M	$541.3M	$641.4M
Total Liabilities	$4.674B	$4.329B	$4.294B
YoY Change	7.96%	5.92%	10.8%
SHAREHOLDERS EQUITY
Retained Earnings	$361.6M	$327.6M	$322.0M
YoY Change	10.39%	5.82%	5.02%
Common Stock	$648.0K	$609.0K	$609.0K
YoY Change	6.4%	0.0%	0.0%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$191.2M	$159.6M	$159.2M
YoY Change	19.8%	-0.88%	5.47%
Treasury Stock Shares	13.93M shares	11.67M shares	11.64M shares
Shareholders Equity	$753.2M	$712.6M	$702.3M
YoY Change
Total Liabilities & Shareholders Equity	$5.427B	$5.042B	$4.997B
YoY Change	7.64%	5.73%	9.69%

Cashflow Statement

Concept	2021 Q2	2020 Q2	2020 Q1
OPERATING ACTIVITIES
Net Income	$19.79M	$10.79M	$4.551M
YoY Change	83.4%	31.56%	-48.11%
Depreciation, Depletion And Amortization	$1.030M	$860.0K	$860.0K
YoY Change	19.77%	2.38%	2.38%
Cash From Operating Activities	$4.790M	$14.17M	$11.95M
YoY Change	-66.2%	120.37%	24.09%
INVESTING ACTIVITIES
Capital Expenditures	-$740.0K	-$410.0K	$806.0K
YoY Change	80.49%	-67.46%	113.79%
Acquisitions
YoY Change
Other Investing Activities	$230.8M	-$45.74M	$21.65M
YoY Change	-604.5%	-80.93%	-124.27%
Cash From Investing Activities	$230.0M	-$46.16M	$20.84M
YoY Change	-598.33%	-80.85%	-123.26%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net			$0.00
YoY Change
Debt Paid & Issued, Net			$361.0M
YoY Change			1344.0%
Cash From Financing Activities	-169.2M	28.19M	-$65.91M
YoY Change	-700.21%	-85.6%	-174.87%
NET CHANGE
Cash From Operating Activities	4.790M	14.17M	$11.95M
Cash From Investing Activities	230.0M	-46.16M	$20.84M
Cash From Financing Activities	-169.2M	28.19M	-$65.91M
Net Change In Cash	65.62M	-3.800M	-$33.12M
YoY Change	-1826.84%	-90.24%	-510.75%
FREE CASH FLOW
Cash From Operating Activities	$4.790M	$14.17M	$11.95M
Capital Expenditures	-$740.0K	-$410.0K	$806.0K
Free Cash Flow	$5.530M	$14.58M	$11.14M
YoY Change	-62.07%	89.6%	20.44%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
	dei	Entity Central Index Key EntityCentralIndexKey	0001493225
	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2021
	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q2
	dei	Amendment Flag AmendmentFlag	false
CY2020	us-gaap	Accounting Standards Update Extensible List AccountingStandardsUpdateExtensibleList	http://fasb.org/us-gaap/2021-01-31#AccountingStandardsUpdate201613Member
	dei	Document Type DocumentType	10-Q
	dei	Document Quarterly Report DocumentQuarterlyReport	true
	dei	Document Period End Date DocumentPeriodEndDate	2021-06-30
	dei	Document Transition Report DocumentTransitionReport	false
	dei	Entity File Number EntityFileNumber	001-35791
	dei	Entity Registrant Name EntityRegistrantName	Northfield Bancorp, Inc.
	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	80-0882592
	dei	Entity Address Address Line1 EntityAddressAddressLine1	581 Main Street,
	dei	Entity Address City Or Town EntityAddressCityOrTown	Woodbridge,
	dei	Entity Address State Or Province EntityAddressStateOrProvince	NJ
	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	07095
	dei	City Area Code CityAreaCode	732
	dei	Local Phone Number LocalPhoneNumber	499-7200
	dei	Security12b Title Security12bTitle	Common stock, par value $0.01 per share
	dei	Trading Symbol TradingSymbol	NFBK
	dei	Security Exchange Name SecurityExchangeName	NASDAQ
	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
	dei	Entity Filer Category EntityFilerCategory	Accelerated Filer
	dei	Entity Small Business EntitySmallBusiness	false
	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
	dei	Entity Shell Company EntityShellCompany	false
CY2021Q3	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	50805455	shares
CY2021Q2	us-gaap	Cash And Due From Banks CashAndDueFromBanks	18681000	USD
CY2020Q4	us-gaap	Cash And Due From Banks CashAndDueFromBanks	16115000	USD
CY2021Q2	us-gaap	Interest Bearing Deposits In Banks InterestBearingDepositsInBanks	174503000	USD
CY2020Q4	us-gaap	Interest Bearing Deposits In Banks InterestBearingDepositsInBanks	71429000	USD
CY2021Q2	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	193184000	USD
CY2020Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	87544000	USD
CY2021Q2	us-gaap	Trading Securities Debt TradingSecuritiesDebt	12743000	USD
CY2020Q4	us-gaap	Trading Securities Debt TradingSecuritiesDebt	12291000	USD
CY2021Q2	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	0	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	1097423000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	1264805000	USD
CY2021Q2	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	6417000	USD
CY2020Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	7234000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	6703000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	7574000	USD
CY2021Q2	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss DebtSecuritiesHeldToMaturityAllowanceForCreditLoss	0	USD
CY2021Q2	us-gaap	Equity Securities Fv Ni And Without Readily Determinable Fair Value EquitySecuritiesFvNiAndWithoutReadilyDeterminableFairValue	219000	USD
CY2020Q4	us-gaap	Equity Securities Fv Ni And Without Readily Determinable Fair Value EquitySecuritiesFvNiAndWithoutReadilyDeterminableFairValue	253000	USD
CY2021Q2	us-gaap	Loans Receivable Held For Sale Amount LoansReceivableHeldForSaleAmount	0	USD
CY2020Q4	us-gaap	Loans Receivable Held For Sale Amount LoansReceivableHeldForSaleAmount	19895000	USD
CY2021Q2	us-gaap	Notes Receivable Gross NotesReceivableGross	3817273000	USD
CY2020Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	3823238000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	39493000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	37607000	USD
CY2021Q2	us-gaap	Notes Receivable Net NotesReceivableNet	3777780000	USD
CY2020Q4	us-gaap	Notes Receivable Net NotesReceivableNet	3785631000	USD
CY2021Q2	us-gaap	Accrued Investment Income Receivable AccruedInvestmentIncomeReceivable	14521000	USD
CY2020Q4	us-gaap	Accrued Investment Income Receivable AccruedInvestmentIncomeReceivable	14690000	USD
CY2021Q2	us-gaap	Bank Owned Life Insurance BankOwnedLifeInsurance	163628000	USD
CY2020Q4	us-gaap	Bank Owned Life Insurance BankOwnedLifeInsurance	161924000	USD
CY2021Q2	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	24508000	USD
CY2020Q4	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	28641000	USD
CY2021Q2	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	34574000	USD
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	36741000	USD
CY2021Q2	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	27268000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	28188000	USD
CY2021Q2	us-gaap	Goodwill Goodwill	41012000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	41320000	USD
CY2021Q2	us-gaap	Other Assets OtherAssets	33633000	USD
CY2020Q4	us-gaap	Other Assets OtherAssets	25387000	USD
CY2021Q2	us-gaap	Assets Assets	5426910000	USD
CY2020Q4	us-gaap	Assets Assets	5514544000	USD
CY2021Q2	us-gaap	Deposits Deposits	4108269000	USD
CY2020Q4	us-gaap	Deposits Deposits	4076551000	USD
CY2021Q2	us-gaap	Securities Sold Under Agreements To Repurchase SecuritiesSoldUnderAgreementsToRepurchase	50000000	USD
CY2020Q4	us-gaap	Securities Sold Under Agreements To Repurchase SecuritiesSoldUnderAgreementsToRepurchase	75000000	USD
CY2021Q2	us-gaap	Other Borrowings OtherBorrowings	420329000	USD
CY2020Q4	us-gaap	Other Borrowings OtherBorrowings	516789000	USD
CY2021Q2	us-gaap	Operating Lease Liability OperatingLeaseLiability	40721000	USD
CY2020Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	42734000	USD
CY2021Q2	us-gaap	Advance Payments By Borrowers For Taxes And Insurance AdvancePaymentsByBorrowersForTaxesAndInsurance	24203000	USD
CY2020Q4	us-gaap	Advance Payments By Borrowers For Taxes And Insurance AdvancePaymentsByBorrowersForTaxesAndInsurance	19677000	USD
CY2021Q2	us-gaap	Accounts Payable And Other Accrued Liabilities AccountsPayableAndOtherAccruedLiabilities	30178000	USD
CY2020Q4	us-gaap	Accounts Payable And Other Accrued Liabilities AccountsPayableAndOtherAccruedLiabilities	29812000	USD
CY2021Q2	us-gaap	Liabilities Liabilities	4673700000	USD
CY2020Q4	us-gaap	Liabilities Liabilities	4760563000	USD
CY2021Q2	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.01
CY2020Q4	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.01
CY2021Q2	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	25000000	shares
CY2020Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	25000000	shares
CY2020Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2021Q2	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2020Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2021Q2	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2021Q2	us-gaap	Preferred Stock Value PreferredStockValue	0	USD
CY2020Q4	us-gaap	Preferred Stock Value PreferredStockValue	0	USD
CY2021Q2	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2020Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2021Q2	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	150000000	shares
CY2020Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	150000000	shares
CY2021Q2	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	64770875	shares
CY2020Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	64770875	shares
CY2021Q2	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	50843651	shares
CY2020Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	52209897	shares
CY2021Q2	us-gaap	Common Stock Value CommonStockValue	648000	USD
CY2020Q4	us-gaap	Common Stock Value CommonStockValue	648000	USD
CY2021Q2	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	589664000	USD
CY2020Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	590506000	USD
CY2021Q2	us-gaap	Employee Stock Ownership Plan Esop Deferred Shares EmployeeStockOwnershipPlanESOPDeferredShares	18040000	USD
CY2020Q4	us-gaap	Employee Stock Ownership Plan Esop Deferred Shares EmployeeStockOwnershipPlanESOPDeferredShares	18529000	USD
CY2021Q2	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	361638000	USD
CY2020Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	338093000	USD
CY2021Q2	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	10455000	USD
CY2020Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	13160000	USD
CY2021Q2	us-gaap	Treasury Stock Shares TreasuryStockShares	13927224	shares
CY2020Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	12560978	shares
CY2021Q2	us-gaap	Treasury Stock Value TreasuryStockValue	191155000	USD
CY2020Q4	us-gaap	Treasury Stock Value TreasuryStockValue	169897000	USD
CY2021Q2	us-gaap	Stockholders Equity StockholdersEquity	753210000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	753981000	USD
CY2021Q2	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	5426910000	USD
CY2020Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	5514544000	USD
CY2021Q2	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	39699000	USD
CY2020Q2	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	35343000	USD
	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	80976000	USD
	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	70680000	USD
CY2021Q2	us-gaap	Interest Income Securities Mortgage Backed InterestIncomeSecuritiesMortgageBacked	2682000	USD
CY2020Q2	us-gaap	Interest Income Securities Mortgage Backed InterestIncomeSecuritiesMortgageBacked	4304000	USD
	us-gaap	Interest Income Securities Mortgage Backed InterestIncomeSecuritiesMortgageBacked	5641000	USD
	us-gaap	Interest Income Securities Mortgage Backed InterestIncomeSecuritiesMortgageBacked	9926000	USD
CY2021Q2	us-gaap	Interest Income Securities Corporate Debt Operating InterestIncomeSecuritiesCorporateDebtOperating	484000	USD
CY2020Q2	us-gaap	Interest Income Securities Corporate Debt Operating InterestIncomeSecuritiesCorporateDebtOperating	777000	USD
	us-gaap	Interest Income Securities Corporate Debt Operating InterestIncomeSecuritiesCorporateDebtOperating	908000	USD
	us-gaap	Interest Income Securities Corporate Debt Operating InterestIncomeSecuritiesCorporateDebtOperating	1801000	USD
CY2021Q2	us-gaap	Interest Income Federal Home Loan Bank Advances InterestIncomeFederalHomeLoanBankAdvances	336000	USD
CY2020Q2	us-gaap	Interest Income Federal Home Loan Bank Advances InterestIncomeFederalHomeLoanBankAdvances	456000	USD
	us-gaap	Interest Income Federal Home Loan Bank Advances InterestIncomeFederalHomeLoanBankAdvances	706000	USD
	us-gaap	Interest Income Federal Home Loan Bank Advances InterestIncomeFederalHomeLoanBankAdvances	1033000	USD
CY2021Q2	us-gaap	Interest Income Deposits With Financial Institutions InterestIncomeDepositsWithFinancialInstitutions	35000	USD
CY2020Q2	us-gaap	Interest Income Deposits With Financial Institutions InterestIncomeDepositsWithFinancialInstitutions	31000	USD
	us-gaap	Interest Income Deposits With Financial Institutions InterestIncomeDepositsWithFinancialInstitutions	72000	USD
	us-gaap	Interest Income Deposits With Financial Institutions InterestIncomeDepositsWithFinancialInstitutions	203000	USD
CY2021Q2	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	43236000	USD
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	78863000	USD
CY2020Q2	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	40911000	USD
	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	88303000	USD
	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	83643000	USD
CY2021Q2	us-gaap	Interest Expense Deposits InterestExpenseDeposits	1671000	USD
CY2020Q2	us-gaap	Interest Expense Deposits InterestExpenseDeposits	7473000	USD
	us-gaap	Interest Expense Deposits InterestExpenseDeposits	3541000	USD
	us-gaap	Interest Expense Deposits InterestExpenseDeposits	16752000	USD
CY2021Q2	us-gaap	Interest Expense Borrowings InterestExpenseBorrowings	2878000	USD
CY2020Q2	us-gaap	Interest Expense Borrowings InterestExpenseBorrowings	3208000	USD
	us-gaap	Interest Expense Borrowings InterestExpenseBorrowings	5899000	USD
	us-gaap	Interest Expense Borrowings InterestExpenseBorrowings	6728000	USD
CY2021Q2	us-gaap	Interest Expense InterestExpense	4549000	USD
CY2020Q2	us-gaap	Interest Expense InterestExpense	10681000	USD
	us-gaap	Interest Expense InterestExpense	9440000	USD
	us-gaap	Interest Expense InterestExpense	23480000	USD
CY2021Q2	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	38687000	USD
CY2020Q2	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	30230000	USD
	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	84938000	USD
	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	50059000	USD
CY2021Q2	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1327000	USD
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	60163000	USD
CY2021Q2	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-3701000	USD
CY2020Q2	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	1921000	USD
	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-6075000	USD
	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	10104000	USD
CY2021Q2	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	42388000	USD
CY2020Q2	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	28309000	USD
CY2020Q2	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	666000	USD
	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	2524000	USD
	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1786000	USD
CY2021Q2	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	857000	USD
CY2020Q2	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	865000	USD
	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	1705000	USD
	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	1741000	USD
CY2021Q2	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	509000	USD
CY2020Q2	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	73000	USD
	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	606000	USD
	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	60000	USD
CY2021Q2	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	807000	USD
CY2020Q2	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	1626000	USD
	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	1171000	USD
	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	-366000	USD
CY2021Q2	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	1401000	USD
CY2020Q2	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	665000	USD
	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	1401000	USD
	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	665000	USD
CY2021Q2	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	15000	USD
CY2020Q2	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	343000	USD
	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	145000	USD
	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	460000	USD
CY2021Q2	us-gaap	Noninterest Income NoninterestIncome	4916000	USD
CY2020Q2	us-gaap	Noninterest Income NoninterestIncome	4238000	USD
	us-gaap	Noninterest Income NoninterestIncome	7552000	USD
	us-gaap	Noninterest Income NoninterestIncome	4346000	USD
CY2021Q2	us-gaap	Labor And Related Expense LaborAndRelatedExpense	10806000	USD
CY2020Q2	us-gaap	Labor And Related Expense LaborAndRelatedExpense	10444000	USD
	us-gaap	Labor And Related Expense LaborAndRelatedExpense	21338000	USD
	us-gaap	Labor And Related Expense LaborAndRelatedExpense	17733000	USD
CY2021Q2	us-gaap	Occupancy Net OccupancyNet	3500000	USD
CY2020Q2	us-gaap	Occupancy Net OccupancyNet	3018000	USD
	us-gaap	Occupancy Net OccupancyNet	7201000	USD
	us-gaap	Occupancy Net OccupancyNet	6078000	USD
CY2021Q2	us-gaap	Equipment Expense EquipmentExpense	442000	USD
CY2020Q2	us-gaap	Equipment Expense EquipmentExpense	349000	USD
	us-gaap	Equipment Expense EquipmentExpense	879000	USD
	us-gaap	Equipment Expense EquipmentExpense	682000	USD
CY2021Q2	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	1798000	USD
CY2020Q2	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	1612000	USD
	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	3430000	USD
	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	3072000	USD
CY2021Q2	us-gaap	Professional Fees ProfessionalFees	832000	USD
CY2020Q2	us-gaap	Professional Fees ProfessionalFees	1045000	USD
	us-gaap	Professional Fees ProfessionalFees	1738000	USD
	us-gaap	Professional Fees ProfessionalFees	2154000	USD
CY2021Q2	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	684000	USD
CY2020Q2	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	343000	USD
	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	1149000	USD
	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	1161000	USD
CY2021Q2	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	346000	USD
CY2020Q2	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	216000	USD
	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	721000	USD
	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	216000	USD
CY2021Q2	us-gaap	Other Noninterest Expense OtherNoninterestExpense	1463000	USD
CY2020Q2	us-gaap	Other Noninterest Expense OtherNoninterestExpense	828000	USD
	us-gaap	Other Noninterest Expense OtherNoninterestExpense	2978000	USD
	us-gaap	Other Noninterest Expense OtherNoninterestExpense	2441000	USD
CY2021Q2	us-gaap	Noninterest Expense NoninterestExpense	19871000	USD
CY2020Q2	us-gaap	Noninterest Expense NoninterestExpense	17855000	USD
	us-gaap	Noninterest Expense NoninterestExpense	39434000	USD
	us-gaap	Noninterest Expense NoninterestExpense	33537000	USD
CY2021Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	27433000	USD
CY2020Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	14692000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	53056000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	20868000	USD
CY2021Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	7639000	USD
CY2020Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	3899000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	14585000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	5524000	USD
CY2021Q2	us-gaap	Net Income Loss NetIncomeLoss	19794000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	10793000	USD
	us-gaap	Net Income Loss NetIncomeLoss	38471000	USD
	us-gaap	Net Income Loss NetIncomeLoss	15344000	USD
CY2021Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.40
CY2020Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.23
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.78
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.33
CY2021Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.40
CY2020Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.23
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.78
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.33
CY2021Q2	us-gaap	Net Income Loss NetIncomeLoss	19794000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	10793000	USD
	us-gaap	Net Income Loss NetIncomeLoss	38471000	USD
	us-gaap	Net Income Loss NetIncomeLoss	15344000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-2006000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	5603000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-3150000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	13913000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	509000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	73000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	606000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	60000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	-2515000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	5530000	USD
	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	-3756000	USD
	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	13853000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-560000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	1568000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-881000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	3894000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	143000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	20000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	170000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	17000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-1812000	USD
CY2020Q2	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	12.24
CY2020Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	3982000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-2705000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	9976000	USD
CY2021Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	17982000	USD
CY2020Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	14775000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	35766000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	25320000	USD
CY2020Q1	us-gaap	Stockholders Equity StockholdersEquity	702316000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	10793000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	3982000	USD
CY2020Q2	us-gaap	Amortization Of Esop Award AmortizationOfESOPAward	327000	USD
CY2020Q2	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	433000	USD
CY2020Q2	us-gaap	Restricted Stock Award Forfeitures RestrictedStockAwardForfeitures	0	USD
CY2020Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.11
CY2020Q2	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.11
CY2020Q2	us-gaap	Dividends Common Stock DividendsCommonStock	5168000	USD
CY2020Q2	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	107000	USD
CY2020Q2	us-gaap	Stockholders Equity StockholdersEquity	712576000	USD
CY2021Q1	us-gaap	Stockholders Equity StockholdersEquity	754565000	USD
CY2021Q2	us-gaap	Net Income Loss NetIncomeLoss	19794000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-1812000	USD
CY2021Q2	us-gaap	Amortization Of Esop Award AmortizationOfESOPAward	491000	USD
CY2021Q2	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	260000	USD
CY2021Q2	us-gaap	Restricted Stock Award Forfeitures RestrictedStockAwardForfeitures	0	USD
CY2021Q2	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	1007000	USD
CY2021Q2	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.13
CY2021Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.13
CY2021Q2	us-gaap	Dividends Common Stock DividendsCommonStock	6392000	USD
CY2021Q2	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	16.32
CY2021Q2	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	14703000	USD
CY2021Q2	us-gaap	Stockholders Equity StockholdersEquity	753210000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	695853000	USD
	us-gaap	Net Income Loss NetIncomeLoss	15344000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	9976000	USD
	us-gaap	Amortization Of Esop Award AmortizationOfESOPAward	773000	USD
	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	881000	USD
	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	0	USD
	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	175000	USD
	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.22
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.22
	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	12.24
	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	107000	USD
CY2020Q2	us-gaap	Stockholders Equity StockholdersEquity	712576000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	753981000	USD
	us-gaap	Net Income Loss NetIncomeLoss	38471000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-2705000	USD
	us-gaap	Amortization Of Esop Award AmortizationOfESOPAward	903000	USD
	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	504000	USD
	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	0	USD
	us-gaap	Restricted Stock Award Forfeitures RestrictedStockAwardForfeitures	0	USD
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.24
	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.24
	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	15.11
CY2021Q2	us-gaap	Stockholders Equity StockholdersEquity	753210000	USD
	us-gaap	Net Income Loss NetIncomeLoss	38471000	USD
	us-gaap	Net Income Loss NetIncomeLoss	15344000	USD
	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-6075000	USD
	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	10104000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	1407000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	1654000	USD
	us-gaap	Depreciation Nonproduction DepreciationNonproduction	1945000	USD
	us-gaap	Depreciation Nonproduction DepreciationNonproduction	1612000	USD
	nfbk	Amortization Of Premiums And Deferred Loan Costs AmortizationOfPremiumsAndDeferredLoanCosts	621000	USD
	nfbk	Amortization Of Premiums And Deferred Loan Costs AmortizationOfPremiumsAndDeferredLoanCosts	1900000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	101000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	110000	USD
	nfbk	Operating Lease Right Of Use Asset Amortization OperatingLeaseRightOfUseAssetAmortization	2167000	USD
	nfbk	Operating Lease Right Of Use Asset Amortization OperatingLeaseRightOfUseAssetAmortization	2166000	USD
	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	1705000	USD
	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	1741000	USD
	us-gaap	Gain Loss On Sale Of Notes Receivable GainLossOnSaleOfNotesReceivable	1401000	USD
	us-gaap	Gain Loss On Sale Of Notes Receivable GainLossOnSaleOfNotesReceivable	665000	USD
	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	606000	USD
	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	60000	USD
	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	1171000	USD
	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	-366000	USD
	us-gaap	Increase Decrease In Trading Securities IncreaseDecreaseInTradingSecurities	-719000	USD
	us-gaap	Increase Decrease In Trading Securities IncreaseDecreaseInTradingSecurities	-762000	USD
	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	-169000	USD
	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	-1584000	USD
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	10020000	USD
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	3325000	USD
	us-gaap	Increase Decrease In Other Accounts Payable And Accrued Liabilities IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities	366000	USD
	us-gaap	Increase Decrease In Other Accounts Payable And Accrued Liabilities IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities	-3691000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	24988000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	26120000	USD
	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	117546000	USD
	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	200613000	USD
	us-gaap	Proceeds From Sale Of Finance Receivables ProceedsFromSaleOfFinanceReceivables	151559000	USD
	us-gaap	Proceeds From Sale Of Finance Receivables ProceedsFromSaleOfFinanceReceivables	48165000	USD
	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	220000	USD
	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	10497000	USD
	nfbk	Redemptions Of Federal Home Loan Bank Stock RedemptionsOfFederalHomeLoanBankStock	4353000	USD
	nfbk	Redemptions Of Federal Home Loan Bank Stock RedemptionsOfFederalHomeLoanBankStock	20610000	USD
	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	213761000	USD
	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	132052000	USD
	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	0	USD
	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	24000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	280050000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	232838000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	788000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	106000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	95472000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	12623000	USD
	nfbk	Proceeds From Sale Of Equity Securities ProceedsFromSaleOfEquitySecurities	34000	USD
	nfbk	Proceeds From Sale Of Equity Securities ProceedsFromSaleOfEquitySecurities	2035000	USD
	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	1021000	USD
	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	2716000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	1025000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	1223000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	200725000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-25316000	USD
	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	31718000	USD
	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	213425000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	11839000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	10319000	USD
	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	1815000	USD
	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	175000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	24833000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	107000	USD
	us-gaap	Increase Decrease In Advance Payments By Borrowers For Taxes And Insurance IncreaseDecreaseInAdvancePaymentsByBorrowersForTaxesAndInsurance	4526000	USD
	us-gaap	Increase Decrease In Advance Payments By Borrowers For Taxes And Insurance IncreaseDecreaseInAdvancePaymentsByBorrowersForTaxesAndInsurance	-163000	USD
	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	265000	USD
	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	370267000	USD
	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	121725000	USD
	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	611000000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-120073000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-37722000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	105640000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-36918000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	87544000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	147818000	USD
CY2021Q2	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	193184000	USD
CY2020Q2	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	110900000	USD
	us-gaap	Interest Paid Net InterestPaidNet	9833000	USD
	us-gaap	Interest Paid Net InterestPaidNet	24845000	USD
	us-gaap	Income Taxes Paid IncomeTaxesPaid	19100000	USD
	us-gaap	Income Taxes Paid IncomeTaxesPaid	7375000	USD
	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	2392000	USD
	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	291000	USD
	us-gaap	Financing Receivable Reclassification To Held For Sale FinancingReceivableReclassificationToHeldForSale	131883000	USD
	us-gaap	Financing Receivable Reclassification To Held For Sale FinancingReceivableReclassificationToHeldForSale	47500000	USD
	us-gaap	Transfer Of Loans Held For Sale To Portfolio Loans1 TransferOfLoansHeldForSaleToPortfolioLoans1	1612000	USD
	us-gaap	Transfer Of Loans Held For Sale To Portfolio Loans1 TransferOfLoansHeldForSaleToPortfolioLoans1	0	USD
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	100000	USD
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	0	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	0	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	3028000	USD
CY2021Q2	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	1083047000	USD
CY2021Q2	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	15315000	USD
CY2021Q2	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	939000	USD
CY2020Q2	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	12600000	USD
CY2020Q2	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	74000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	1097423000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	1246673000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	18862000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	730000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	1264805000	USD
CY2021Q2	us-gaap	Debt Securities Available For Sale Restricted DebtSecuritiesAvailableForSaleRestricted	557000000.0	USD
CY2021Q2	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	89600000	USD
CY2021Q2	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	509000	USD
CY2021Q2	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	0	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	95500000	USD
	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	606000	USD
	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	0	USD
CY2020Q2	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	1000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	12600000	USD
	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	74000	USD
	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	14000	USD
CY2021Q2	us-gaap	Debt Securities Trading Realized Gain Loss DebtSecuritiesTradingRealizedGainLoss	807000	USD
	us-gaap	Debt Securities Trading Realized Gain Loss DebtSecuritiesTradingRealizedGainLoss	1200000	USD
CY2020Q2	us-gaap	Debt Securities Trading Realized Gain Loss DebtSecuritiesTradingRealizedGainLoss	1600000	USD
	us-gaap	Debt Securities Trading Realized Gain Loss DebtSecuritiesTradingRealizedGainLoss	-366000	USD
CY2021Q2	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	931000	USD
CY2021Q2	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	173513000	USD
CY2021Q2	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	8000	USD
CY2021Q2	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	383000	USD
CY2021Q2	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	939000	USD
CY2021Q2	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	173896000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	719000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	242146000	USD
CY2021Q2	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	6417000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	286000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	0	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	11000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	459000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	730000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	242605000	USD
CY2021Q2	us-gaap	Debt Securities Available For Sale Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLoss	1900000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	6703000	USD
CY2020Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	7234000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	340000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	0	USD
CY2020Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	7574000	USD
	us-gaap	Debt Securities Held To Maturity Sold Amount DebtSecuritiesHeldToMaturitySoldAmount	0	USD
	us-gaap	Debt Securities Held To Maturity Sold Amount DebtSecuritiesHeldToMaturitySoldAmount	0	USD
CY2020Q4	us-gaap	Loans Receivable Held For Sale Amount LoansReceivableHeldForSaleAmount	19900000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Restricted HeldToMaturitySecuritiesRestricted	6400000	USD
CY2020Q4	nfbk	Debt Securities Held To Maturity Unrealized Loss Position Number Of Positions DebtSecuritiesHeldToMaturityUnrealizedLossPositionNumberOfPositions	0	security
CY2021Q2	nfbk	Debt Securities Held To Maturity Unrealized Loss Position Number Of Positions DebtSecuritiesHeldToMaturityUnrealizedLossPositionNumberOfPositions	0	security
CY2021Q2	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest	0	USD
CY2021Q2	us-gaap	Debt Securities Held To Maturity Accrued Interest After Allowance For Credit Loss DebtSecuritiesHeldToMaturityAccruedInterestAfterAllowanceForCreditLoss	19400	USD
CY2021Q2	us-gaap	Equity Securities Fv Ni And Without Readily Determinable Fair Value EquitySecuritiesFvNiAndWithoutReadilyDeterminableFairValue	219000	USD
CY2020Q4	us-gaap	Equity Securities Fv Ni And Without Readily Determinable Fair Value EquitySecuritiesFvNiAndWithoutReadilyDeterminableFairValue	253000	USD
CY2021Q2	us-gaap	Notes Receivable Gross NotesReceivableGross	3817273000	USD
CY2020Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	3823238000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	39493000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	37607000	USD
CY2021Q2	us-gaap	Notes Receivable Net NotesReceivableNet	3777780000	USD
CY2020Q4	us-gaap	Notes Receivable Net NotesReceivableNet	3785631000	USD
CY2021Q2	us-gaap	Loans Receivable Held For Sale Amount LoansReceivableHeldForSaleAmount	0	USD
CY2021Q2	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	8100000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	8500000	USD
	nfbk	Delinquent Status Classification Criteria Days Minimum DelinquentStatusClassificationCriteriaDaysMinimum	P90D
	nfbk	Delinquent Status Classification Criteria Days Minimum DelinquentStatusClassificationCriteriaDaysMinimum	P90D
CY2021Q2	nfbk	Principal Balance Threshold For Non Accrual Status PrincipalBalanceThresholdForNonAccrualStatus	500000	USD
CY2021Q2	nfbk	Loans Deemed To Be Impaired Non Accrual Amount LoansDeemedToBeImpairedNonAccrualAmount	4900000	USD
CY2020Q4	nfbk	Loans Deemed To Be Impaired Non Accrual Amount LoansDeemedToBeImpairedNonAccrualAmount	5500000	USD
CY2021Q2	nfbk	Principal Balance Threshold For Non Accrual Status PrincipalBalanceThresholdForNonAccrualStatus	500000	USD
CY2021Q2	nfbk	Loans On Non Accrual Status With Principal Balances Below Threshold Definition Of Impaired Loan LoansOnNonAccrualStatusWithPrincipalBalancesBelowThresholdDefinitionOfImpairedLoan	3200000	USD
CY2020Q4	nfbk	Loans On Non Accrual Status With Principal Balances Below Threshold Definition Of Impaired Loan LoansOnNonAccrualStatusWithPrincipalBalancesBelowThresholdDefinitionOfImpairedLoan	3000000.0	USD
CY2020	nfbk	Delinquent Status Classification Criteria Days Minimum DelinquentStatusClassificationCriteriaDaysMinimum	P90D
	nfbk	Delinquent Status Classification Criteria Days Minimum DelinquentStatusClassificationCriteriaDaysMinimum	P90D
CY2021Q2	us-gaap	Financing Receivable Recorded Investment90 Days Past Due And Still Accruing FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing	731000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment90 Days Past Due And Still Accruing FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing	1100000	USD
CY2021Q2	us-gaap	Loans Receivable Held For Sale Amount LoansReceivableHeldForSaleAmount	0	USD
CY2020Q4	us-gaap	Loans Receivable Held For Sale Amount LoansReceivableHeldForSaleAmount	19900000	USD
CY2020	nfbk	Delinquent Status Classification Criteria Days Minimum DelinquentStatusClassificationCriteriaDaysMinimum	P90D
	nfbk	Delinquent Status Classification Criteria Days Minimum DelinquentStatusClassificationCriteriaDaysMinimum	P90D
CY2021Q2	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	8124000	USD
CY2021Q2	nfbk	Financing Receivable Nonaccrual Unpaid Principal Balance FinancingReceivableNonaccrualUnpaidPrincipalBalance	9127000	USD
CY2021Q2	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	4365000	USD
CY2021Q2	us-gaap	Financing Receivable Nonaccrual Interest Income FinancingReceivableNonaccrualInterestIncome	46000	USD
	us-gaap	Financing Receivable Nonaccrual Interest Income FinancingReceivableNonaccrualInterestIncome	95000	USD
CY2020Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	13242000	USD
CY2020Q4	us-gaap	Impaired Financing Receivable Unpaid Principal Balance ImpairedFinancingReceivableUnpaidPrincipalBalance	15512000	USD
CY2020Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	73000	USD
CY2020Q4	us-gaap	Impaired Financing Receivable With No Related Allowance Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment	7800000	USD
CY2020Q2	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	20202000	USD
CY2020Q2	us-gaap	Impaired Financing Receivable Interest Income Cash Basis Method ImpairedFinancingReceivableInterestIncomeCashBasisMethod	277000	USD
	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	20451000	USD
	us-gaap	Impaired Financing Receivable Interest Income Cash Basis Method ImpairedFinancingReceivableInterestIncomeCashBasisMethod	436000	USD
CY2021Q2	nfbk	Financing Receivable Impaired Secured By Collateral FinancingReceivableImpairedSecuredByCollateral	9800000	USD
CY2020Q4	nfbk	Financing Receivable Impaired Secured By Collateral FinancingReceivableImpairedSecuredByCollateral	10200000	USD
	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	0	loan
CY2021Q2	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	0	loan
	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	3	loan
	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	731000	USD
	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	731000	USD
CY2020Q2	nfbk	Financing Receivable Modification Number Of Borrowers FinancingReceivableModificationNumberOfBorrowers	3	borrower
CY2021Q2	nfbk	Trouble Debt Restructuring Amount TroubleDebtRestructuringAmount	11500000	USD
CY2020Q4	nfbk	Trouble Debt Restructuring Amount TroubleDebtRestructuringAmount	12100000	USD
	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0	contract
	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0	contract
CY2021Q2	us-gaap	Financing Receivable Accrued Interest After Allowance For Credit Loss FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss	12600000	USD
CY2021Q2	nfbk	Financing Receivable Threshold Individually Evaluated For Impairment FinancingReceivableThresholdIndividuallyEvaluatedForImpairment	500000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	68000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	73000	USD
CY2021Q1	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	1702000	USD
CY2020Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	808000	USD
CY2021Q2	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	106000	USD
	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	263000	USD
CY2021Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	1808000	USD
CY2021Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	1808000	USD
CY2021Q1	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	43197000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	12000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	9000	USD
CY2021Q2	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-3701000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	39493000	USD
CY2020Q1	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	36800000	USD
CY2020Q2	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	221000	USD
CY2020Q2	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	20000	USD
CY2020Q2	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	1921000	USD
CY2020Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	38520000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	37607000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	2444000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	52000	USD
	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-6075000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	39493000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	28707000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	691000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	400000	USD
	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	10104000	USD
CY2020Q2	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	38520000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	68000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment	39425000	USD
CY2021Q2	us-gaap	Notes Receivable Gross NotesReceivableGross	3817273000	USD
CY2021Q2	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	12490000	USD
CY2021Q2	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	3672075000	USD
CY2021Q2	nfbk	Financing Receivable Not Evaluated For Impairment FinancingReceivableNotEvaluatedForImpairment	132708000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	73000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment	37534000	USD
CY2020Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	3823238000	USD
CY2020Q4	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	13242000	USD
CY2020Q4	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	3683461000	USD
CY2020Q4	nfbk	Financing Receivable Not Evaluated For Impairment FinancingReceivableNotEvaluatedForImpairment	126535000	USD
CY2021Q2	us-gaap	Noninterest Bearing Deposit Liabilities NoninterestBearingDepositLiabilities	826823000	USD
CY2020Q4	us-gaap	Noninterest Bearing Deposit Liabilities NoninterestBearingDepositLiabilities	695831000	USD
CY2021Q2	us-gaap	Deposits Negotiable Order Of Withdrawal Now DepositsNegotiableOrderOfWithdrawalNOW	979788000	USD
CY2020Q4	us-gaap	Deposits Negotiable Order Of Withdrawal Now DepositsNegotiableOrderOfWithdrawalNOW	905208000	USD
CY2021Q2	us-gaap	Deposits Savings Deposits DepositsSavingsDeposits	1788545000	USD
CY2020Q4	us-gaap	Deposits Savings Deposits DepositsSavingsDeposits	1953885000	USD
CY2021Q2	us-gaap	Time Deposits TimeDeposits	513113000	USD
CY2020Q4	us-gaap	Time Deposits TimeDeposits	521627000	USD
CY2021Q2	us-gaap	Deposits Deposits	4108269000	USD
CY2020Q4	us-gaap	Deposits Deposits	4076551000	USD
CY2021Q2	us-gaap	Interest Expense Domestic Deposit Liabilities Demand InterestExpenseDomesticDepositLiabilitiesDemand	845000	USD
CY2020Q2	us-gaap	Interest Expense Domestic Deposit Liabilities Demand InterestExpenseDomesticDepositLiabilitiesDemand	2894000	USD
	us-gaap	Interest Expense Domestic Deposit Liabilities Demand InterestExpenseDomesticDepositLiabilitiesDemand	1777000	USD
	us-gaap	Interest Expense Domestic Deposit Liabilities Demand InterestExpenseDomesticDepositLiabilitiesDemand	6967000	USD
CY2021Q2	us-gaap	Interest Expense Domestic Deposit Liabilities Certificates Of Deposit InterestExpenseDomesticDepositLiabilitiesCertificatesOfDeposit	826000	USD
CY2020Q2	us-gaap	Interest Expense Domestic Deposit Liabilities Certificates Of Deposit InterestExpenseDomesticDepositLiabilitiesCertificatesOfDeposit	4579000	USD
	us-gaap	Interest Expense Domestic Deposit Liabilities Certificates Of Deposit InterestExpenseDomesticDepositLiabilitiesCertificatesOfDeposit	1764000	USD
	us-gaap	Interest Expense Domestic Deposit Liabilities Certificates Of Deposit InterestExpenseDomesticDepositLiabilitiesCertificatesOfDeposit	9785000	USD
CY2021Q2	us-gaap	Interest Expense Deposits InterestExpenseDeposits	1671000	USD
CY2020Q2	us-gaap	Interest Expense Deposits InterestExpenseDeposits	7473000	USD
	us-gaap	Interest Expense Deposits InterestExpenseDeposits	3541000	USD
	us-gaap	Interest Expense Deposits InterestExpenseDeposits	16752000	USD
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	2214193	shares
CY2020Q4	nfbk	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageGrantDateFairValue	4.01
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	13.94
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P3Y11M15D
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	41090	shares
	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Options Forfeited Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue	3.96
	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	13.62
	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	138605	shares
	nfbk	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageGrantDateFairValue	3.92
	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	13.78
CY2021Q2	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	2034498	shares
CY2021Q2	nfbk	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageGrantDateFairValue	4.01
CY2021Q2	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	13.96
	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P3Y5M23D
CY2021Q2	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	2017419	shares
CY2021Q2	nfbk	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageGrantDateFairValue	4.01
CY2021Q2	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	13.94
	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1	P3Y5M19D
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	104010	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	15.91
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	176930	shares
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	12.59
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	38470	shares
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	15.81
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	5585	shares
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	15.28
CY2021Q2	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	236885	shares
CY2021Q2	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	13.46
CY2021Q2	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	261000	USD
CY2020Q2	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	432000	USD
	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	504000	USD
	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	880000	USD
CY2021Q2	us-gaap	Loans Receivable Fair Value Disclosure LoansReceivableFairValueDisclosure	4705000	USD
CY2020Q4	us-gaap	Loans Receivable Fair Value Disclosure LoansReceivableFairValueDisclosure	5325000	USD
CY2021Q2	nfbk	Other Real Estate Owned Fair Value Disclosure OtherRealEstateOwnedFairValueDisclosure	100000	USD
CY2020Q4	nfbk	Other Real Estate Owned Fair Value Disclosure OtherRealEstateOwnedFairValueDisclosure	0	USD
CY2021Q2	nfbk	Principal Amount Outstanding Of Impaired Loans Heldfor Investment Heldfor Sale PrincipalAmountOutstandingOfImpairedLoansHeldforInvestmentHeldforSale	6800000	USD
CY2020Q4	nfbk	Principal Amount Outstanding Of Impaired Loans Heldfor Investment Heldfor Sale PrincipalAmountOutstandingOfImpairedLoansHeldforInvestmentHeldforSale	7400000	USD
CY2021Q2	nfbk	Estimated Fair Value Of Impaired Loans Held For Investment EstimatedFairValueOfImpairedLoansHeldForInvestment	4700000	USD
CY2020Q4	nfbk	Estimated Fair Value Of Impaired Loans Held For Investment EstimatedFairValueOfImpairedLoansHeldForInvestment	5300000	USD
	nfbk	Impaired Financing Receivable Reserve Increase Decrease ImpairedFinancingReceivableReserveIncreaseDecrease	5000	USD
	nfbk	Impaired Financing Receivable Reserve Increase Decrease ImpairedFinancingReceivableReserveIncreaseDecrease	177000	USD
	nfbk	Impaired Financing Receivables Charge Off ImpairedFinancingReceivablesChargeOff	2400000	USD
	nfbk	Impaired Financing Receivables Charge Off ImpairedFinancingReceivablesChargeOff	291000	USD
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	100000	USD
CY2020Q4	us-gaap	Loans Held For Sale Fair Value Disclosure LoansHeldForSaleFairValueDisclosure	19895000	USD
CY2021Q2	us-gaap	Net Income Loss NetIncomeLoss	19794000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	10793000	USD
	us-gaap	Net Income Loss NetIncomeLoss	38471000	USD
	us-gaap	Net Income Loss NetIncomeLoss	15344000	USD
CY2021Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	48907585	shares
CY2020Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	46837473	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	49216157	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	46814647	shares
CY2021Q2	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	400076	shares
CY2020Q2	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	34017	shares
	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	252651	shares
	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	112857	shares
CY2021Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	49307661	shares
CY2020Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	46871490	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	49468808	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	46927504	shares
CY2021Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.40
CY2020Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.23
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.78
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.33
CY2021Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.40
CY2020Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.23
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.78
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.33
CY2021Q2	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	125744	shares
CY2020Q2	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	2316695	shares
	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	564061	shares
	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1659262	shares
CY2021Q2	us-gaap	Lease Cost LeaseCost	2463000	USD
CY2021Q2	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	34600000	USD
CY2021Q2	us-gaap	Operating Lease Liability OperatingLeaseLiability	40700000	USD
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	36700000	USD
CY2020Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	42700000	USD
CY2021Q2	us-gaap	Operating Lease Cost OperatingLeaseCost	1453000	USD
CY2020Q2	us-gaap	Operating Lease Cost OperatingLeaseCost	1423000	USD
	us-gaap	Operating Lease Cost OperatingLeaseCost	2908000	USD
	us-gaap	Operating Lease Cost OperatingLeaseCost	2862000	USD
CY2021Q2	us-gaap	Variable Lease Cost VariableLeaseCost	1010000	USD
CY2020Q2	us-gaap	Variable Lease Cost VariableLeaseCost	956000	USD
	us-gaap	Variable Lease Cost VariableLeaseCost	2245000	USD
	us-gaap	Variable Lease Cost VariableLeaseCost	1500000	USD
CY2020Q2	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	0	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	0	USD
CY2021Q2	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0361
CY2020Q2	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0359
CY2020Q2	us-gaap	Lease Cost LeaseCost	2379000	USD
	us-gaap	Lease Cost LeaseCost	5153000	USD
	us-gaap	Lease Cost LeaseCost	4362000	USD
CY2021Q2	us-gaap	Operating Lease Payments OperatingLeasePayments	1691000	USD
CY2020Q2	us-gaap	Operating Lease Payments OperatingLeasePayments	1524000	USD
	us-gaap	Operating Lease Payments OperatingLeasePayments	3399000	USD
	us-gaap	Operating Lease Payments OperatingLeasePayments	3069000	USD
CY2021Q2	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	0	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	3028000	USD
CY2021Q2	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P12Y2M26D
CY2020Q2	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P12Y7M17D
CY2021Q2	us-gaap	Lessee Operating Lease Liability Payments Remainder Of Fiscal Year LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear	2937000	USD
CY2021Q2	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	5550000	USD
CY2021Q2	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	5504000	USD
CY2021Q2	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	5067000	USD
CY2021Q2	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	4710000	USD
CY2021Q2	nfbk	Lessee Operating Lease Liability Payments Due After Year Four LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFour	28196000	USD
CY2021Q2	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	51964000	USD
CY2021Q2	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	11243000	USD
CY2021Q2	us-gaap	Operating Lease Liability OperatingLeaseLiability	40721000	USD
CY2021Q2	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1327000	USD
CY2020Q2	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	666000	USD
	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	2524000	USD
	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1786000	USD
CY2021Q2	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	857000	USD
CY2020Q2	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	865000	USD
	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	1705000	USD
	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	1741000	USD
CY2021Q2	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	509000	USD
CY2020Q2	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	73000	USD
	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	606000	USD
	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	60000	USD
CY2021Q2	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	807000	USD
CY2020Q2	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	1626000	USD
	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	1171000	USD
	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	-366000	USD
CY2021Q2	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	1401000	USD
CY2020Q2	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	665000	USD
	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	1401000	USD
	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	665000	USD
CY2021Q2	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	0	USD
CY2020Q2	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	308000	USD
	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	0	USD
	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	384000	USD
CY2021Q2	us-gaap	Revenue Not From Contract With Customer Other RevenueNotFromContractWithCustomerOther	15000	USD
CY2020Q2	us-gaap	Revenue Not From Contract With Customer Other RevenueNotFromContractWithCustomerOther	35000	USD
	us-gaap	Revenue Not From Contract With Customer Other RevenueNotFromContractWithCustomerOther	145000	USD
	us-gaap	Revenue Not From Contract With Customer Other RevenueNotFromContractWithCustomerOther	76000	USD
CY2021Q2	us-gaap	Noninterest Income NoninterestIncome	4916000	USD
CY2020Q2	us-gaap	Noninterest Income NoninterestIncome	4238000	USD
	us-gaap	Noninterest Income NoninterestIncome	7552000	USD
	us-gaap	Noninterest Income NoninterestIncome	4346000	USD
CY2021Q2	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	0	USD
	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	0	USD
CY2020Q2	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	308000	USD
	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	384000	USD

Files In Submission

Name	View Source	Status
0001493225-21-000098-index-headers.html	Edgar Link	pending
0001493225-21-000098-index.html	Edgar Link	pending
0001493225-21-000098.txt	Edgar Link	pending
0001493225-21-000098-xbrl.zip	Edgar Link	pending
ex311-2021x6x30.htm	Edgar Link	pending
ex312-2021x6x30.htm	Edgar Link	pending
ex32-2021x6x30.htm	Edgar Link	pending
FilingSummary.xml	Edgar Link	unprocessable
Financial_Report.xlsx	Edgar Link	pending
MetaLinks.json	Edgar Link	pending
nfbk-20210630.htm	Edgar Link	pending
nfbk-20210630.xsd	Edgar Link	pending
nfbk-20210630_cal.xml	Edgar Link	unprocessable
nfbk-20210630_def.xml	Edgar Link	unprocessable
nfbk-20210630_htm.xml	Edgar Link	completed
nfbk-20210630_lab.xml	Edgar Link	unprocessable
nfbk-20210630_pre.xml	Edgar Link	unprocessable
R1.htm	Edgar Link	pending
R10.htm	Edgar Link	pending
R11.htm	Edgar Link	pending
R12.htm	Edgar Link	pending
R13.htm	Edgar Link	pending
R14.htm	Edgar Link	pending
R15.htm	Edgar Link	pending
R16.htm	Edgar Link	pending
R17.htm	Edgar Link	pending
R18.htm	Edgar Link	pending
R19.htm	Edgar Link	pending
R2.htm	Edgar Link	pending
R20.htm	Edgar Link	pending
R21.htm	Edgar Link	pending
R22.htm	Edgar Link	pending
R23.htm	Edgar Link	pending
R24.htm	Edgar Link	pending
R25.htm	Edgar Link	pending
R26.htm	Edgar Link	pending
R27.htm	Edgar Link	pending
R28.htm	Edgar Link	pending
R29.htm	Edgar Link	pending
R3.htm	Edgar Link	pending
R30.htm	Edgar Link	pending
R31.htm	Edgar Link	pending
R32.htm	Edgar Link	pending
R33.htm	Edgar Link	pending
R34.htm	Edgar Link	pending
R35.htm	Edgar Link	pending
R36.htm	Edgar Link	pending
R37.htm	Edgar Link	pending
R38.htm	Edgar Link	pending
R39.htm	Edgar Link	pending
R4.htm	Edgar Link	pending
R40.htm	Edgar Link	pending
R41.htm	Edgar Link	pending
R42.htm	Edgar Link	pending
R43.htm	Edgar Link	pending
R44.htm	Edgar Link	pending
R45.htm	Edgar Link	pending
R46.htm	Edgar Link	pending
R47.htm	Edgar Link	pending
R48.htm	Edgar Link	pending
R49.htm	Edgar Link	pending
R5.htm	Edgar Link	pending
R50.htm	Edgar Link	pending
R51.htm	Edgar Link	pending
R52.htm	Edgar Link	pending
R53.htm	Edgar Link	pending
R54.htm	Edgar Link	pending
R55.htm	Edgar Link	pending
R56.htm	Edgar Link	pending
R57.htm	Edgar Link	pending
R58.htm	Edgar Link	pending
R59.htm	Edgar Link	pending
R6.htm	Edgar Link	pending
R60.htm	Edgar Link	pending
R61.htm	Edgar Link	pending
R62.htm	Edgar Link	pending
R63.htm	Edgar Link	pending
R64.htm	Edgar Link	pending
R65.htm	Edgar Link	pending
R66.htm	Edgar Link	pending
R67.htm	Edgar Link	pending
R68.htm	Edgar Link	pending
R69.htm	Edgar Link	pending
R7.htm	Edgar Link	pending
R70.htm	Edgar Link	pending
R71.htm	Edgar Link	pending
R72.htm	Edgar Link	pending
R73.htm	Edgar Link	pending
R74.htm	Edgar Link	pending
R75.htm	Edgar Link	pending
R76.htm	Edgar Link	pending
R77.htm	Edgar Link	pending
R78.htm	Edgar Link	pending
R8.htm	Edgar Link	pending
R9.htm	Edgar Link	pending
report.css	Edgar Link	pending
Show.js	Edgar Link	pending

Create your account

Find Stocks Worth Researching

Deeply Understand Businesses

Value Businesses Intelligently

$NFBK
Northfield Bancorp, Inc. Stock $nfbk

2021 Q2 Form 10-Q Financial Statement

#000149322521000098 Filed on August 09, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$NFBK Northfield Bancorp, Inc. Stock $nfbk

2021 Q2 Form 10-Q Financial Statement

#000149322521000098 Filed on August 09, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$NFBK
Northfield Bancorp, Inc. Stock $nfbk