$NFBK
Northfield Bancorp, Inc. Stock $nfbk

$nfbk Overview Financials Valuation SEC Filings Company Website

2023 Q1 Form 10-K Financial Statement

#000149322523000055 Filed on March 01, 2023

Income Statement

Concept	2023 Q1	2022 Q4	2022
Revenue	$1.380M		$5.705M
YoY Change	-96.57%		-96.69%
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	$940.0K	$934.0K	$3.600M
YoY Change	-5.91%	-8.43%	-7.69%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense	$15.03M		$21.38M
YoY Change	352.06%		28.43%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$16.24M	$19.68M	$84.86M
YoY Change	-16.61%	-10.2%	-12.63%
Income Tax	$4.529M	$5.538M	$23.74M
% Of Pretax Income	27.89%	28.14%	27.98%
Net Earnings	$11.71M	$14.14M	$61.12M
YoY Change	-17.13%	-12.2%	-13.5%
Net Earnings / Revenue	848.33%		1071.32%
Basic Earnings Per Share	$0.26		$1.32
Diluted Earnings Per Share	$0.26	$308.8K	$1.316M
COMMON SHARES
Basic Shares Outstanding	46.85M shares	47.77M shares	46.23M shares
Diluted Shares Outstanding	44.93M shares		46.44M shares

Balance Sheet

Concept	2023 Q1	2022 Q4	2022
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$159.0M	$45.80M
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	$24.67M	$59.13M	$59.13M
YoY Change	-2.69%	127.98%	-1.28%
Goodwill	$41.01M	$41.00M
YoY Change	0.0%	-0.03%
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	$5.663B	$5.601B	$5.601B
YoY Change	2.66%	3.14%	3.15%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$30.85M	$26.00M	$26.00M
YoY Change	2.71%	4.4%	4.4%
Accrued Expenses	$76.63M	$78.83M	$78.83M
YoY Change	9.29%	5.53%	5.53%
Deferred Revenue
YoY Change
Short-Term Debt	$25.00M	$25.00M	$25.00M
YoY Change	-50.0%	-50.0%	-55.99%
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$132.5M	$104.8M	$104.8M
YoY Change	32.28%	5.25%	5.25%
LONG-TERM LIABILITIES
Long-Term Debt	$985.0M	$619.9M	$619.9M
YoY Change	183.16%	66.72%
Other Long-Term Liabilities
YoY Change
Total Long-Term Liabilities	$985.0M	$619.9M	$619.9M
YoY Change	183.16%	66.72%
TOTAL LIABILITIES
Total Short-Term Liabilities	$132.5M	$104.8M	$104.8M
Total Long-Term Liabilities	$985.0M	$619.9M	$619.9M
Total Liabilities	$4.965B	$4.900B	$4.900B
YoY Change	3.42%	4.46%	4.46%
SHAREHOLDERS EQUITY
Retained Earnings	$424.1M	$418.4M
YoY Change	8.93%	9.7%
Common Stock	$648.0K	$648.0K
YoY Change	0.0%	0.0%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$698.2M	$701.4M	$701.4M
YoY Change
Total Liabilities & Shareholders Equity	$5.663B	$5.601B	$5.601B
YoY Change	2.66%	3.14%	3.15%

Cashflow Statement

Concept	2023 Q1	2022 Q4	2022
OPERATING ACTIVITIES
Net Income	$11.71M	$14.14M	$61.12M
YoY Change	-17.13%	-12.2%	-13.5%
Depreciation, Depletion And Amortization	$940.0K	$934.0K	$3.600M
YoY Change	-5.91%	-8.43%	-7.69%
Cash From Operating Activities	$17.75M	$24.97M	$83.33M
YoY Change	-9.42%	16.9%	28.68%
INVESTING ACTIVITIES
Capital Expenditures	$739.0K	$352.0K	$2.552M
YoY Change	102.47%	-200.57%	55.8%
Acquisitions
YoY Change
Other Investing Activities	$50.98M	$41.53M	-$277.7M
YoY Change	-167.56%	-134.15%	-420.51%
Cash From Investing Activities	$50.24M	$41.17M	-$280.2M
YoY Change	-166.26%	-133.77%	-429.68%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net			$120.0M
YoY Change			-29.43%
Cash From Financing Activities	$45.17M	-91.01M	$151.6M
YoY Change	-55.13%	-606.46%	-203.68%
NET CHANGE
Cash From Operating Activities	$17.75M	24.97M	$83.33M
Cash From Investing Activities	$50.24M	41.17M	-$280.2M
Cash From Financing Activities	$45.17M	-91.01M	$151.6M
Net Change In Cash	$113.2M	-24.87M	-$45.27M
YoY Change	154.59%	-69.9%	-1384.59%
FREE CASH FLOW
Cash From Operating Activities	$17.75M	$24.97M	$83.33M
Capital Expenditures	$739.0K	$352.0K	$2.552M
Free Cash Flow	$17.01M	$24.62M	$80.78M
YoY Change	-11.55%	13.39%	27.97%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
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CY2022	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2022
CY2022	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
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CY2022	dei	Document Period End Date DocumentPeriodEndDate	2022-12-31
CY2022	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
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CY2022	dei	Entity File Number EntityFileNumber	001-35791
CY2022	dei	Entity Registrant Name EntityRegistrantName	Northfield Bancorp, Inc.
CY2022	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
CY2022	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	80-0882592
CY2022	dei	Entity Address Address Line1 EntityAddressAddressLine1	581 Main Street,
CY2022	dei	Entity Address City Or Town EntityAddressCityOrTown	Woodbridge,
CY2022	dei	Entity Address State Or Province EntityAddressStateOrProvince	NJ
CY2022	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	07095
CY2022	dei	City Area Code CityAreaCode	732
CY2022	dei	Local Phone Number LocalPhoneNumber	499-7200
CY2022	dei	Security12b Title Security12bTitle	Common Stock, par value $0.01 per share
CY2022	dei	Trading Symbol TradingSymbol	NFBK
CY2022	dei	Security Exchange Name SecurityExchangeName	NASDAQ
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CY2021	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	1495000	usd
CY2020	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	327000	usd
CY2022	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	-2206000	usd
CY2021	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	1703000	usd
CY2020	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	1601000	usd
CY2022	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	453000	usd
CY2021	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	1401000	usd
CY2020	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	665000	usd
CY2022	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	338000	usd
CY2021	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	357000	usd
CY2020	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	1138000	usd
CY2022	us-gaap	Noninterest Income NoninterestIncome	7983000	usd
CY2021	us-gaap	Noninterest Income NoninterestIncome	14453000	usd
CY2020	us-gaap	Noninterest Income NoninterestIncome	11472000	usd
CY2022	us-gaap	Labor And Related Expense LaborAndRelatedExpense	41961000	usd
CY2021	us-gaap	Labor And Related Expense LaborAndRelatedExpense	43677000	usd
CY2020	us-gaap	Labor And Related Expense LaborAndRelatedExpense	41437000	usd
CY2022	us-gaap	Occupancy Net OccupancyNet	13241000	usd
CY2021	us-gaap	Occupancy Net OccupancyNet	13956000	usd
CY2020	us-gaap	Occupancy Net OccupancyNet	15152000	usd
CY2022	us-gaap	Equipment Expense EquipmentExpense	1730000	usd
CY2021	us-gaap	Equipment Expense EquipmentExpense	1737000	usd
CY2020	us-gaap	Equipment Expense EquipmentExpense	1519000	usd
CY2022	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	7415000	usd
CY2021	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	6784000	usd
CY2020	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	8123000	usd
CY2022	us-gaap	Professional Fees ProfessionalFees	3846000	usd
CY2021	us-gaap	Professional Fees ProfessionalFees	3596000	usd
CY2020	us-gaap	Professional Fees ProfessionalFees	4141000	usd
CY2022	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	2159000	usd
CY2021	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	2358000	usd
CY2020	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	2088000	usd
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	26473000	usd
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	13037000	usd
CY2022	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	1407000	usd
CY2021	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	1365000	usd
CY2020	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	885000	usd
CY2022	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-1061000	usd
CY2021	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	307000	usd
CY2020	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	0	usd
CY2022	us-gaap	Other Noninterest Expense OtherNoninterestExpense	6250000	usd
CY2021	us-gaap	Other Noninterest Expense OtherNoninterestExpense	5379000	usd
CY2020	us-gaap	Other Noninterest Expense OtherNoninterestExpense	5168000	usd
CY2022	us-gaap	Noninterest Expense NoninterestExpense	76948000	usd
CY2021	us-gaap	Noninterest Expense NoninterestExpense	79159000	usd
CY2020	us-gaap	Noninterest Expense NoninterestExpense	78513000	usd
CY2022	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	84859000	usd
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	97127000	usd
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	50025000	usd
CY2022	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	23740000	usd
CY2022	us-gaap	Net Income Loss NetIncomeLoss	61119000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	70654000	usd
CY2020	us-gaap	Net Income Loss NetIncomeLoss	36988000	usd
CY2022	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.32
CY2022	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.32
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.46
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.76
CY2022	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.32
CY2022	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.32
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.45
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.76
CY2022	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	46234122	shares
CY2022	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	46234122	shares
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	48416495	shares
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	48721504	shares
CY2022	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	46438119	shares
CY2022	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	46438119	shares
CY2021	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	48754263	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	48785963	shares
CY2022	us-gaap	Net Income Loss NetIncomeLoss	61119000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	70654000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	70654000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	70654000	usd
CY2020	us-gaap	Net Income Loss NetIncomeLoss	36988000	usd
CY2020	us-gaap	Net Income Loss NetIncomeLoss	36988000	usd
CY2022	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-69876000	usd
CY2021	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-13916000	usd
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	12077000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	279000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	1495000	usd
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	327000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	-70155000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	-15411000	usd
CY2020	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	11750000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-172000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	0	usd
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	0	usd
CY2022	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	-69983000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	-15411000	usd
CY2020	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	11750000	usd
CY2022	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-19558000	usd
CY2021	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-3895000	usd
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	3380000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	79000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	419000	usd
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	91000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	-48000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	0	usd
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	0	usd
CY2022	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-50394000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-11097000	usd
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	8461000	usd
CY2022	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	10725000	usd
CY2021	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	59557000	usd
CY2020	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	45449000	usd
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	695853000	usd
CY2020	us-gaap	Net Income Loss NetIncomeLoss	36988000	usd
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	8461000	usd
CY2020	us-gaap	Amortization Of Esop Award AmortizationOfESOPAward	1780000	usd
CY2020	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	1432000	usd
CY2020	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	0	usd
CY2020	us-gaap	Restricted Stock Award Forfeitures RestrictedStockAwardForfeitures	0	usd
CY2020	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	175000	usd
CY2020	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.44
CY2020	us-gaap	Dividends Common Stock DividendsCommonStock	21476000	usd
CY2020	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	41173000	usd
CY2020	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	11.59
CY2020	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	10405000	usd
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	753981000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	70654000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-11097000	usd
CY2021	us-gaap	Amortization Of Esop Award AmortizationOfESOPAward	2649000	usd
CY2021	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	994000	usd
CY2021	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	0	usd
CY2021	us-gaap	Restricted Stock Award Forfeitures RestrictedStockAwardForfeitures	0	usd
CY2021	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	3409000	usd
CY2021	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.50
CY2021	us-gaap	Dividends Common Stock DividendsCommonStock	24299000	usd
CY2021	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	15.91
CY2021	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	53321000	usd
CY2021Q4	us-gaap	Stockholders Equity StockholdersEquity	739883000	usd
CY2022	us-gaap	Net Income Loss NetIncomeLoss	61119000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-50394000	usd
CY2022	us-gaap	Amortization Of Esop Award AmortizationOfESOPAward	2375000	usd
CY2022	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	1753000	usd
CY2022	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	0	usd
CY2022	us-gaap	Restricted Stock Award Forfeitures RestrictedStockAwardForfeitures	0	usd
CY2022	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	1662000	usd
CY2022	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.52
CY2022	us-gaap	Dividends Common Stock DividendsCommonStock	24127000	usd
CY2022	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	14.72
CY2022	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	30881000	usd
CY2022Q4	us-gaap	Stockholders Equity StockholdersEquity	701390000	usd
CY2022	us-gaap	Net Income Loss NetIncomeLoss	61119000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	70654000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	70654000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	70654000	usd
CY2020	us-gaap	Net Income Loss NetIncomeLoss	36988000	usd
CY2020	us-gaap	Net Income Loss NetIncomeLoss	36988000	usd
CY2022	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	4482000	usd
CY2021	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	-6184000	usd
CY2020	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	12742000	usd
CY2022	us-gaap	Share Based Compensation ShareBasedCompensation	4128000	usd
CY2021	us-gaap	Share Based Compensation ShareBasedCompensation	3643000	usd
CY2020	us-gaap	Share Based Compensation ShareBasedCompensation	3212000	usd
CY2022	us-gaap	Depreciation Nonproduction DepreciationNonproduction	3645000	usd
CY2021	us-gaap	Depreciation Nonproduction DepreciationNonproduction	3889000	usd
CY2020	us-gaap	Depreciation Nonproduction DepreciationNonproduction	3878000	usd
CY2022	nfbk	Amortization Of Premiums And Deferred Loan Costs AmortizationOfPremiumsAndDeferredLoanCosts	9306000	usd
CY2021	nfbk	Amortization Of Premiums And Deferred Loan Costs AmortizationOfPremiumsAndDeferredLoanCosts	2587000	usd
CY2020	nfbk	Amortization Of Premiums And Deferred Loan Costs AmortizationOfPremiumsAndDeferredLoanCosts	4073000	usd
CY2022	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	112000	usd
CY2021	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	0	usd
CY2020	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	0	usd
CY2022	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	174000	usd
CY2021	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	200000	usd
CY2020	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	229000	usd
CY2022	us-gaap	Operating Lease Right Of Use Asset Amortization Expense OperatingLeaseRightOfUseAssetAmortizationExpense	4626000	usd
CY2021	us-gaap	Operating Lease Right Of Use Asset Amortization Expense OperatingLeaseRightOfUseAssetAmortizationExpense	4395000	usd
CY2020	us-gaap	Operating Lease Right Of Use Asset Amortization Expense OperatingLeaseRightOfUseAssetAmortizationExpense	4586000	usd
CY2022	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	3414000	usd
CY2021	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	4103000	usd
CY2020	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	3774000	usd
CY2022	us-gaap	Gain Loss On Sale Of Loans And Leases GainLossOnSaleOfLoansAndLeases	453000	usd
CY2021	us-gaap	Gain Loss On Sale Of Loans And Leases GainLossOnSaleOfLoansAndLeases	1401000	usd
CY2020	us-gaap	Gain Loss On Sale Of Loans And Leases GainLossOnSaleOfLoansAndLeases	665000	usd
CY2022	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	3544000	usd
CY2021	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	0	usd
CY2020	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	0	usd
CY2022	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	3364000	usd
CY2021	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	0	usd
CY2020	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	0	usd
CY2022	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	279000	usd
CY2021	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	1495000	usd
CY2020	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	327000	usd
CY2022	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	-2206000	usd
CY2021	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	1703000	usd
CY2020	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	1601000	usd
CY2022	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	17000	usd
CY2021	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	0	usd
CY2020	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	0	usd
CY2022	us-gaap	Increase Decrease In Trading Securities IncreaseDecreaseInTradingSecurities	-504000	usd
CY2021	us-gaap	Increase Decrease In Trading Securities IncreaseDecreaseInTradingSecurities	-533000	usd
CY2020	us-gaap	Increase Decrease In Trading Securities IncreaseDecreaseInTradingSecurities	-532000	usd
CY2022	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	2924000	usd
CY2021	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	-118000	usd
CY2020	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	-1334000	usd
CY2022	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	3673000	usd
CY2021	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	14531000	usd
CY2020	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-1294000	usd
CY2022	us-gaap	Increase Decrease In Deferred Income Taxes IncreaseDecreaseInDeferredIncomeTaxes	625000	usd
CY2021	us-gaap	Increase Decrease In Deferred Income Taxes IncreaseDecreaseInDeferredIncomeTaxes	-3159000	usd
CY2020	us-gaap	Increase Decrease In Deferred Income Taxes IncreaseDecreaseInDeferredIncomeTaxes	3058000	usd
CY2022	us-gaap	Increase Decrease In Other Accounts Payable And Accrued Liabilities IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities	4234000	usd
CY2021	us-gaap	Increase Decrease In Other Accounts Payable And Accrued Liabilities IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities	4998000	usd
CY2020	us-gaap	Increase Decrease In Other Accounts Payable And Accrued Liabilities IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities	-4229000	usd
CY2022	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	83331000	usd
CY2021	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	64759000	usd
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	55214000	usd
CY2022	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	430849000	usd
CY2021	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	105455000	usd
CY2020	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	276616000	usd
CY2022	us-gaap	Payments To Acquire Finance Receivables PaymentsToAcquireFinanceReceivables	10183000	usd
CY2021	us-gaap	Payments To Acquire Finance Receivables PaymentsToAcquireFinanceReceivables	0	usd
CY2020	us-gaap	Payments To Acquire Finance Receivables PaymentsToAcquireFinanceReceivables	0	usd
CY2022	us-gaap	Proceeds From Sale Of Finance Receivables ProceedsFromSaleOfFinanceReceivables	2796000	usd
CY2021	us-gaap	Proceeds From Sale Of Finance Receivables ProceedsFromSaleOfFinanceReceivables	151559000	usd
CY2020	us-gaap	Proceeds From Sale Of Finance Receivables ProceedsFromSaleOfFinanceReceivables	48165000	usd
CY2022	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	44564000	usd
CY2021	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	220000	usd
CY2020	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	10497000	usd
CY2022	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	36518000	usd
CY2021	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	6525000	usd
CY2020	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	21735000	usd
CY2022	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	168973000	usd
CY2021	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	746967000	usd
CY2020	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	572342000	usd
CY2022	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	5046000	usd
CY2021	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	5089000	usd
CY2020	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	27000	usd
CY2022	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	305027000	usd
CY2021	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	454414000	usd
CY2020	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	556920000	usd
CY2022	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	720000	usd
CY2021	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	1879000	usd
CY2020	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	1462000	usd
CY2022	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	6237000	usd
CY2021	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	0	usd
CY2020	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	0	usd
CY2022	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	41479000	usd
CY2021	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	328966000	usd
CY2020	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	23628000	usd
CY2022	nfbk	Proceeds From Sale Of Equity Securities ProceedsFromSaleOfEquitySecurities	0	usd
CY2021	nfbk	Proceeds From Sale Of Equity Securities ProceedsFromSaleOfEquitySecurities	0	usd
CY2020	nfbk	Proceeds From Sale Of Equity Securities ProceedsFromSaleOfEquitySecurities	3115000	usd
CY2022	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	1526000	usd
CY2021	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	1021000	usd
CY2020	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	2716000	usd
CY2022	us-gaap	Proceeds From Sale Of Other Real Estate ProceedsFromSaleOfOtherRealEstate	125000	usd
CY2021	us-gaap	Proceeds From Sale Of Other Real Estate ProceedsFromSaleOfOtherRealEstate	0	usd
CY2020	us-gaap	Proceeds From Sale Of Other Real Estate ProceedsFromSaleOfOtherRealEstate	0	usd
CY2022	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	2552000	usd
CY2021	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	1638000	usd
CY2020	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	3059000	usd
CY2022	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	0	usd
CY2021	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	0	usd
CY2020	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	72875000	usd
CY2022	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-280213000	usd
CY2021	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	84995000	usd
CY2021	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	92783000	usd
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-131925000	usd
CY2022	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	-19115000	usd
CY2020	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	313726000	usd
CY2022	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	24127000	usd
CY2021	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	24299000	usd
CY2020	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	21476000	usd
CY2022	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	1662000	usd
CY2021	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	3409000	usd
CY2020	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	175000	usd
CY2022	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	30881000	usd
CY2021	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	53321000	usd
CY2020	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	10405000	usd
CY2022	us-gaap	Increase Decrease In Advance Payments By Borrowers For Taxes And Insurance IncreaseDecreaseInAdvancePaymentsByBorrowersForTaxesAndInsurance	1086000	usd
CY2021	us-gaap	Increase Decrease In Advance Payments By Borrowers For Taxes And Insurance IncreaseDecreaseInAdvancePaymentsByBorrowersForTaxesAndInsurance	5232000	usd
CY2020	us-gaap	Increase Decrease In Advance Payments By Borrowers For Taxes And Insurance IncreaseDecreaseInAdvancePaymentsByBorrowersForTaxesAndInsurance	-368000	usd
CY2022	us-gaap	Proceeds From Issuance Of Subordinated Long Term Debt ProceedsFromIssuanceOfSubordinatedLongTermDebt	60884000	usd
CY2021	us-gaap	Proceeds From Issuance Of Subordinated Long Term Debt ProceedsFromIssuanceOfSubordinatedLongTermDebt	0	usd
CY2020	us-gaap	Proceeds From Issuance Of Subordinated Long Term Debt ProceedsFromIssuanceOfSubordinatedLongTermDebt	0	usd
CY2022	nfbk	Proceeds From Securities Sold Under Agreements To Repurchase ProceedsFromSecuritiesSoldUnderAgreementsToRepurchase	282104000	usd
CY2021	nfbk	Proceeds From Securities Sold Under Agreements To Repurchase ProceedsFromSecuritiesSoldUnderAgreementsToRepurchase	0	usd
CY2020	nfbk	Proceeds From Securities Sold Under Agreements To Repurchase ProceedsFromSecuritiesSoldUnderAgreementsToRepurchase	370785000	usd
CY2022	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	120000000	usd
CY2021	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	170034000	usd
CY2020	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	636000000	usd
CY2022	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	151613000	usd
CY2021	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-146230000	usd
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	16437000	usd
CY2022	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-45269000	usd
CY2021	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	3524000	usd
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-60274000	usd
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	91068000	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
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	45799000	usd
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	91068000	usd
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	87544000	usd
CY2022	us-gaap	Interest Paid Net InterestPaidNet	19282000	usd
CY2021	us-gaap	Interest Paid Net InterestPaidNet	17451000	usd
CY2020	us-gaap	Interest Paid Net InterestPaidNet	39584000	usd
CY2022	us-gaap	Income Taxes Paid IncomeTaxesPaid	22094000	usd
CY2021	us-gaap	Income Taxes Paid IncomeTaxesPaid	28476000	usd
CY2020	us-gaap	Income Taxes Paid IncomeTaxesPaid	15169000	usd
CY2022	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	838000	usd
CY2021	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	2803000	usd
CY2020	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	3842000	usd
CY2022	us-gaap	Transfer Of Portfolio Loans And Leases To Held For Sale1 TransferOfPortfolioLoansAndLeasesToHeldForSale1	2523000	usd
CY2021	us-gaap	Transfer Of Portfolio Loans And Leases To Held For Sale1 TransferOfPortfolioLoansAndLeasesToHeldForSale1	131883000	usd
CY2020	us-gaap	Transfer Of Portfolio Loans And Leases To Held For Sale1 TransferOfPortfolioLoansAndLeasesToHeldForSale1	67395000	usd
CY2022	us-gaap	Transfer Of Loans Held For Sale To Portfolio Loans1 TransferOfLoansHeldForSaleToPortfolioLoans1	0	usd
CY2021	us-gaap	Transfer Of Loans Held For Sale To Portfolio Loans1 TransferOfLoansHeldForSaleToPortfolioLoans1	1612000	usd
CY2020	us-gaap	Transfer Of Loans Held For Sale To Portfolio Loans1 TransferOfLoansHeldForSaleToPortfolioLoans1	0	usd
CY2022	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	0	usd
CY2021	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	100000	usd
CY2020	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	0	usd
CY2022	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	4983000	usd
CY2021	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	1596000	usd
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	3568000	usd
CY2022	us-gaap	Noncash Or Part Noncash Acquisition Investments Acquired1 NoncashOrPartNoncashAcquisitionInvestmentsAcquired1	0	usd
CY2021	us-gaap	Noncash Or Part Noncash Acquisition Investments Acquired1 NoncashOrPartNoncashAcquisitionInvestmentsAcquired1	0	usd
CY2020	us-gaap	Noncash Or Part Noncash Acquisition Investments Acquired1 NoncashOrPartNoncashAcquisitionInvestmentsAcquired1	126931000	usd
CY2022	nfbk	Noncashor Part Noncash Acquisition Loansand Leases Receivable Net NoncashorPartNoncashAcquisitionLoansandLeasesReceivableNet	0	usd
CY2021	nfbk	Noncashor Part Noncash Acquisition Loansand Leases Receivable Net NoncashorPartNoncashAcquisitionLoansandLeasesReceivableNet	0	usd
CY2020	nfbk	Noncashor Part Noncash Acquisition Loansand Leases Receivable Net NoncashorPartNoncashAcquisitionLoansandLeasesReceivableNet	180431000	usd
CY2022	nfbk	Non Cash Or Non Cash Acquisition Accrued Interest Receivable NonCashOrNonCashAcquisitionAccruedInterestReceivable	0	usd
CY2021	nfbk	Non Cash Or Non Cash Acquisition Accrued Interest Receivable NonCashOrNonCashAcquisitionAccruedInterestReceivable	0	usd
CY2020	nfbk	Non Cash Or Non Cash Acquisition Accrued Interest Receivable NonCashOrNonCashAcquisitionAccruedInterestReceivable	1415000	usd
CY2022	nfbk	Noncashor Part Noncash Acquisition Bank Owned Life Insurance NoncashorPartNoncashAcquisitionBankOwnedLifeInsurance	0	usd
CY2021	nfbk	Noncashor Part Noncash Acquisition Bank Owned Life Insurance NoncashorPartNoncashAcquisitionBankOwnedLifeInsurance	0	usd
CY2020	nfbk	Noncashor Part Noncash Acquisition Bank Owned Life Insurance NoncashorPartNoncashAcquisitionBankOwnedLifeInsurance	5714000	usd
CY2022	us-gaap	Noncash Or Part Noncash Acquisition Fixed Assets Acquired1 NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1	0	usd
CY2021	us-gaap	Noncash Or Part Noncash Acquisition Fixed Assets Acquired1 NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1	0	usd
CY2020	us-gaap	Noncash Or Part Noncash Acquisition Fixed Assets Acquired1 NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1	7789000	usd
CY2022	nfbk	Noncashor Part Noncash Acquisition Intangible Assetsincluding Goodwill Acquired NoncashorPartNoncashAcquisitionIntangibleAssetsincludingGoodwillAcquired	0	usd
CY2021	nfbk	Noncashor Part Noncash Acquisition Intangible Assetsincluding Goodwill Acquired NoncashorPartNoncashAcquisitionIntangibleAssetsincludingGoodwillAcquired	0	usd
CY2020	nfbk	Noncashor Part Noncash Acquisition Intangible Assetsincluding Goodwill Acquired NoncashorPartNoncashAcquisitionIntangibleAssetsincludingGoodwillAcquired	2909000	usd
CY2022	us-gaap	Noncash Or Part Noncash Acquisition Other Assets Acquired1 NoncashOrPartNoncashAcquisitionOtherAssetsAcquired1	0	usd
CY2021	us-gaap	Noncash Or Part Noncash Acquisition Other Assets Acquired1 NoncashOrPartNoncashAcquisitionOtherAssetsAcquired1	0	usd
CY2020	us-gaap	Noncash Or Part Noncash Acquisition Other Assets Acquired1 NoncashOrPartNoncashAcquisitionOtherAssetsAcquired1	4702000	usd
CY2022	us-gaap	Noncash Or Part Noncash Acquisition Value Of Assets Acquired1 NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1	0	usd
CY2021	us-gaap	Noncash Or Part Noncash Acquisition Value Of Assets Acquired1 NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1	0	usd
CY2020	us-gaap	Noncash Or Part Noncash Acquisition Value Of Assets Acquired1 NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1	329891000	usd
CY2022	nfbk	Non Cash Or Non Cash Acquisition Deposits Assumed NonCashOrNonCashAcquisitionDepositsAssumed	0	usd
CY2021	nfbk	Non Cash Or Non Cash Acquisition Deposits Assumed NonCashOrNonCashAcquisitionDepositsAssumed	0	usd
CY2020	nfbk	Non Cash Or Non Cash Acquisition Deposits Assumed NonCashOrNonCashAcquisitionDepositsAssumed	354592000	usd
CY2022	us-gaap	Noncash Or Part Noncash Acquisition Other Liabilities Assumed1 NoncashOrPartNoncashAcquisitionOtherLiabilitiesAssumed1	0	usd
CY2021	us-gaap	Noncash Or Part Noncash Acquisition Other Liabilities Assumed1 NoncashOrPartNoncashAcquisitionOtherLiabilitiesAssumed1	0	usd
CY2020	us-gaap	Noncash Or Part Noncash Acquisition Other Liabilities Assumed1 NoncashOrPartNoncashAcquisitionOtherLiabilitiesAssumed1	7001000	usd
CY2022	us-gaap	Noncash Or Part Noncash Acquisition Value Of Liabilities Assumed1 NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1	0	usd
CY2021	us-gaap	Noncash Or Part Noncash Acquisition Value Of Liabilities Assumed1 NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1	0	usd
CY2020	us-gaap	Noncash Or Part Noncash Acquisition Value Of Liabilities Assumed1 NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1	361593000	usd
CY2022	us-gaap	Noncash Or Part Noncash Acquisition Net Nonmonetary Assets Acquired Liabilities Assumed1 NoncashOrPartNoncashAcquisitionNetNonmonetaryAssetsAcquiredLiabilitiesAssumed1	0	usd
CY2021	us-gaap	Noncash Or Part Noncash Acquisition Net Nonmonetary Assets Acquired Liabilities Assumed1 NoncashOrPartNoncashAcquisitionNetNonmonetaryAssetsAcquiredLiabilitiesAssumed1	0	usd
CY2020	us-gaap	Noncash Or Part Noncash Acquisition Net Nonmonetary Assets Acquired Liabilities Assumed1 NoncashOrPartNoncashAcquisitionNetNonmonetaryAssetsAcquiredLiabilitiesAssumed1	-31702000	usd
CY2022	nfbk	Cash And Cash Equivalents Acquired Net Of Cash Paid Related To Acquisition CashAndCashEquivalentsAcquiredNetOfCashPaidRelatedToAcquisition	0	usd
CY2021	nfbk	Cash And Cash Equivalents Acquired Net Of Cash Paid Related To Acquisition CashAndCashEquivalentsAcquiredNetOfCashPaidRelatedToAcquisition		usd
CY2020	nfbk	Cash And Cash Equivalents Acquired Net Of Cash Paid Related To Acquisition CashAndCashEquivalentsAcquiredNetOfCashPaidRelatedToAcquisition	72875000	usd
CY2022	nfbk	Non Cash Or Part Non Cash Acquisition Non Cash Financial Or Equity Instrument Consideration Shares Issued Value NonCashOrPartNonCashAcquisitionNonCashFinancialOrEquityInstrumentConsiderationSharesIssuedValue	0	usd
CY2021	nfbk	Non Cash Or Part Non Cash Acquisition Non Cash Financial Or Equity Instrument Consideration Shares Issued Value NonCashOrPartNonCashAcquisitionNonCashFinancialOrEquityInstrumentConsiderationSharesIssuedValue	0	usd
CY2020	nfbk	Non Cash Or Part Non Cash Acquisition Non Cash Financial Or Equity Instrument Consideration Shares Issued Value NonCashOrPartNonCashAcquisitionNonCashFinancialOrEquityInstrumentConsiderationSharesIssuedValue	41173000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLoss	2800000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLoss	2500000	usd
CY2022Q4	us-gaap	Financing Receivable Accrued Interest After Allowance For Credit Loss FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss	11700000	usd
CY2021Q4	us-gaap	Financing Receivable Accrued Interest After Allowance For Credit Loss FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss	9400000	usd
CY2022Q4	us-gaap	Financing Receivable Accrued Interest After Allowance For Credit Loss FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss	11700000	usd
CY2021Q4	us-gaap	Financing Receivable Accrued Interest After Allowance For Credit Loss FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss	9400000	usd
CY2022	nfbk	Threshold Of Membership Investment Component Percentage ThresholdOfMembershipInvestmentComponentPercentage	0.00125
CY2022	nfbk	Threshold Of Membership Investment Component ThresholdOfMembershipInvestmentComponent	1000	usd
CY2022	nfbk	Activity Based Investment Component As Percentage Of Outstanding Advances ActivityBasedInvestmentComponentAsPercentageOfOutstandingAdvances	0.045
CY2022Q4	us-gaap	Goodwill Goodwill	41000000	usd
CY2022	nfbk	Employee Stock Ownership Plan Esop Debt Structure Direct Loan Repayment Period EmployeeStockOwnershipPlanEsopDebtStructureDirectLoanRepaymentPeriod	P30Y
CY2022	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	203997	shares
CY2021	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	337768	shares
CY2020	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	64459	shares
CY2022Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	1019607000	usd
CY2022Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	3000	usd
CY2022Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	67437000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	952173000	usd
CY2021Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	1205516000	usd
CY2021Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	7824000	usd
CY2021Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	5103000	usd
CY2021Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	1208237000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Restricted DebtSecuritiesAvailableForSaleRestricted	591700000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Restricted DebtSecuritiesAvailableForSaleRestricted	522100000	usd
CY2022	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	41500000	usd
CY2022	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	279000	usd
CY2022	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	0	usd
CY2021	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	329000000	usd
CY2021	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	1500000	usd
CY2021	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	0	usd
CY2020	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	23600000	usd
CY2020	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	350000	usd
CY2020	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	23000	usd
CY2022	us-gaap	Debt Securities Trading Realized Gain Loss DebtSecuritiesTradingRealizedGainLoss	-2200000	usd
CY2022Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest Before Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss	10760000	usd
CY2021	us-gaap	Debt Securities Trading Realized Gain Loss DebtSecuritiesTradingRealizedGainLoss	1700000	usd
CY2020	us-gaap	Debt Securities Trading Realized Gain Loss DebtSecuritiesTradingRealizedGainLoss	1600000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	21199000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	430053000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	46238000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	504194000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	67437000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	934247000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	4637000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	689869000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	466000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	21328000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	5103000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	711197000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLoss	2800000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLoss	2500000	usd
CY2022Q4	nfbk	Debt Securities Held To Maturity Unrealized Loss Position Greater Than Twelve Months Number Of Positions DebtSecuritiesHeldToMaturityUnrealizedLossPositionGreaterThanTwelveMonthsNumberOfPositions	0	security
CY2022Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	90000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	461000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	10389000	usd
CY2021Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest Before Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss	5283000	usd
CY2021Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	192000	usd
CY2021Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	0	usd
CY2021Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	5475000	usd
CY2020	us-gaap	Debt Securities Held To Maturity Sold Amount DebtSecuritiesHeldToMaturitySoldAmount	0	usd
CY2021	us-gaap	Debt Securities Held To Maturity Sold Amount DebtSecuritiesHeldToMaturitySoldAmount	0	usd
CY2022	us-gaap	Debt Securities Held To Maturity Sold Amount DebtSecuritiesHeldToMaturitySoldAmount	0	usd
CY2022Q4	us-gaap	Held To Maturity Securities Restricted HeldToMaturitySecuritiesRestricted	2000000	usd
CY2021Q4	us-gaap	Held To Maturity Securities Restricted HeldToMaturitySecuritiesRestricted	2100000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	461000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	7433000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	0	usd
CY2022Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	0	usd
CY2022Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	461000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue	7433000	usd
CY2022Q4	nfbk	Debt Securities Held To Maturity Unrealized Loss Position Less Than Twelve Months Number Of Positions DebtSecuritiesHeldToMaturityUnrealizedLossPositionLessThanTwelveMonthsNumberOfPositions	9	security
CY2021Q4	nfbk	Debt Securities Held To Maturity Unrealized Loss Position Number Of Positions DebtSecuritiesHeldToMaturityUnrealizedLossPositionNumberOfPositions	0	security
CY2022Q4	us-gaap	Debt Securities Held To Maturity Accrued Interest After Allowance For Credit Loss DebtSecuritiesHeldToMaturityAccruedInterestAfterAllowanceForCreditLoss	39000	usd
CY2021Q4	us-gaap	Debt Securities Held To Maturity Accrued Interest After Allowance For Credit Loss DebtSecuritiesHeldToMaturityAccruedInterestAfterAllowanceForCreditLoss	16000	usd
CY2022Q4	us-gaap	Equity Securities Fv Ni And Without Readily Determinable Fair Value EquitySecuritiesFvNiAndWithoutReadilyDeterminableFairValue	10400000	usd
CY2021Q4	us-gaap	Equity Securities Fv Ni And Without Readily Determinable Fair Value EquitySecuritiesFvNiAndWithoutReadilyDeterminableFairValue	5300000	usd
CY2022Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	4243693000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	3806617000	usd
CY2022Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	42617000	usd
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	38973000	usd
CY2022Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	4201076000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	3767644000	usd
CY2022Q4	us-gaap	Loans Receivable Held For Sale Amount LoansReceivableHeldForSaleAmount	0	usd
CY2021Q4	us-gaap	Loans Receivable Held For Sale Amount LoansReceivableHeldForSaleAmount	0	usd
CY2022Q4	us-gaap	Financing Receivable Excluding Accrued Interest Nonaccrual FinancingReceivableExcludingAccruedInterestNonaccrual	9800000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Nonaccrual FinancingReceivableExcludingAccruedInterestNonaccrual	7600000	usd
CY2022	nfbk	Delinquent Status Classification Criteria Days Minimum DelinquentStatusClassificationCriteriaDaysMinimum	P90D
CY2022	nfbk	Delinquent Status Classification Criteria Days Minimum DelinquentStatusClassificationCriteriaDaysMinimum	P90D
CY2022Q4	nfbk	Principal Balance Threshold For Non Accrual Status PrincipalBalanceThresholdForNonAccrualStatus	500000	usd
CY2022Q4	nfbk	Loans Deemed To Be Impaired Non Accrual Amount LoansDeemedToBeImpairedNonAccrualAmount	5200000	usd
CY2021Q4	nfbk	Loans Deemed To Be Impaired Non Accrual Amount LoansDeemedToBeImpairedNonAccrualAmount	4200000	usd
CY2022Q4	nfbk	Principal Balance Threshold For Non Accrual Status PrincipalBalanceThresholdForNonAccrualStatus	500000	usd
CY2022Q4	nfbk	Loans On Non Accrual Status With Principal Balances Below Threshold Definition Of An Impaired Loan LoansOnNonAccrualStatusWithPrincipalBalancesBelowThresholdDefinitionOfAnImpairedLoan	4600000	usd
CY2021Q4	nfbk	Loans On Non Accrual Status With Principal Balances Below Threshold Definition Of An Impaired Loan LoansOnNonAccrualStatusWithPrincipalBalancesBelowThresholdDefinitionOfAnImpairedLoan	3400000	usd
CY2021	nfbk	Delinquent Status Classification Criteria Days Minimum DelinquentStatusClassificationCriteriaDaysMinimum	P90D
CY2022	nfbk	Delinquent Status Classification Criteria Days Minimum DelinquentStatusClassificationCriteriaDaysMinimum	P90D
CY2022Q4	us-gaap	Financing Receivable Excluding Accrued Interest90 Days Or More Past Due Still Accruing FinancingReceivableExcludingAccruedInterest90DaysOrMorePastDueStillAccruing	425000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest90 Days Or More Past Due Still Accruing FinancingReceivableExcludingAccruedInterest90DaysOrMorePastDueStillAccruing	384000	usd
CY2021	nfbk	Delinquent Status Classification Criteria Days Minimum DelinquentStatusClassificationCriteriaDaysMinimum	P90D
CY2022	nfbk	Delinquent Status Classification Criteria Days Minimum DelinquentStatusClassificationCriteriaDaysMinimum	P90D
CY2022Q4	us-gaap	Financing Receivable Excluding Accrued Interest Nonaccrual FinancingReceivableExcludingAccruedInterestNonaccrual	9813000	usd
CY2022Q4	nfbk	Financing Receivable Excluding Accrued Interest Nonaccrual Unpaid Principal Balance FinancingReceivableExcludingAccruedInterestNonaccrualUnpaidPrincipalBalance	10851000	usd
CY2022Q4	us-gaap	Financing Receivable Excluding Accrued Interest Nonaccrual No Allowance FinancingReceivableExcludingAccruedInterestNonaccrualNoAllowance	5186000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Nonaccrual FinancingReceivableExcludingAccruedInterestNonaccrual	7622000	usd
CY2021Q4	nfbk	Financing Receivable Excluding Accrued Interest Nonaccrual Unpaid Principal Balance FinancingReceivableExcludingAccruedInterestNonaccrualUnpaidPrincipalBalance	8743000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Nonaccrual No Allowance FinancingReceivableExcludingAccruedInterestNonaccrualNoAllowance	4241000	usd
CY2022	us-gaap	Impaired Financing Receivable Interest Income Cash Basis Method ImpairedFinancingReceivableInterestIncomeCashBasisMethod	343000	usd
CY2021	us-gaap	Impaired Financing Receivable Interest Income Cash Basis Method ImpairedFinancingReceivableInterestIncomeCashBasisMethod	175000	usd
CY2022Q4	nfbk	Financing Receivable Impaired Secured By Collateral FinancingReceivableImpairedSecuredByCollateral	7400000	usd
CY2021Q4	nfbk	Financing Receivable Impaired Secured By Collateral FinancingReceivableImpairedSecuredByCollateral	7400000	usd
CY2021	nfbk	Financing Receivable Modification Number Of Borrowers FinancingReceivableModificationNumberOfBorrowers	2	borrower
CY2021	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	96000	usd
CY2021	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	96000	usd
CY2021	nfbk	Financing Receivable Modification Number Of Borrowers FinancingReceivableModificationNumberOfBorrowers	2	borrower
CY2022Q4	nfbk	Trouble Debt Restructuring Amount TroubleDebtRestructuringAmount	7000000.0	usd
CY2021Q4	nfbk	Trouble Debt Restructuring Amount TroubleDebtRestructuringAmount	9000000.0	usd
CY2021	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0	contract
CY2022	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0	contract
CY2022Q4	nfbk	Financing Receivable Threshold Individually Evaluated For Impairment FinancingReceivableThresholdIndividuallyEvaluatedForImpairment	500000	usd
CY2022Q4	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	38200	usd
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	30200	usd
CY2021Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	1852000	usd
CY2020Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	808000	usd
CY2022	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-1061000	usd
CY2021	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	307000	usd
CY2022Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	791000	usd
CY2021Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	1852000	usd
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	38973000	usd
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	37607000	usd
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	28707000	usd
CY2022	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	4482000	usd
CY2021	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	-6184000	usd
CY2020	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	12742000	usd
CY2022	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Recovery FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery	487000	usd
CY2021	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Recovery FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery	278000	usd
CY2020	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Recovery FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery	465000	usd
CY2022	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	1325000	usd
CY2021	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	3081000	usd
CY2020	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	4307000	usd
CY2022Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	42617000	usd
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	38973000	usd
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	37607000	usd
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	38973000	usd
CY2022	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	1325000	usd
CY2022	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Recovery FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery	487000	usd
CY2022	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	4482000	usd
CY2022Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	42617000	usd
CY2022Q4	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	38000	usd
CY2022Q4	us-gaap	Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment	38696000	usd
CY2022Q4	nfbk	Financing Receivable Allowance For Credit Losses Pcd Loans Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesPCDLoansEvaluatedForImpairment	3883000	usd
CY2022Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	4243693000	usd
CY2022Q4	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	8939000	usd
CY2022Q4	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	4218109000	usd
CY2022Q4	nfbk	Financing Receivables Pcd Loans Evaluated For Impairment FinancingReceivablesPCDLoansEvaluatedForImpairment	11502000	usd
CY2022Q4	nfbk	Financing Receivable Not Evaluated For Impairment FinancingReceivableNotEvaluatedForImpairment	5143000	usd
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	37607000	usd
CY2021	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	3081000	usd
CY2021	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Recovery FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery	278000	usd
CY2021	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	-6184000	usd
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	38973000	usd
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	30000	usd
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment	34211000	usd
CY2021Q4	nfbk	Financing Receivable Allowance For Credit Losses Pcd Loans Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesPCDLoansEvaluatedForImpairment	4732000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	3806617000	usd
CY2021Q4	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	9986000	usd
CY2021Q4	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	3740295000	usd
CY2021Q4	nfbk	Financing Receivables Pcd Loans Evaluated For Impairment FinancingReceivablesPCDLoansEvaluatedForImpairment	15819000	usd
CY2021Q4	nfbk	Financing Receivable Not Evaluated For Impairment FinancingReceivableNotEvaluatedForImpairment	40517000	usd
CY2022Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	82875000	usd
CY2021Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	80323000	usd
CY2022Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	58031000	usd
CY2021Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	54386000	usd
CY2022Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	24844000	usd
CY2021Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	25937000	usd
CY2022	us-gaap	Depreciation Depreciation	3600000	usd
CY2021	us-gaap	Depreciation Depreciation	3900000	usd
CY2020	us-gaap	Depreciation Depreciation	3900000	usd
CY2020	nfbk	Impairment Long Lived Asset Held For Use Statement Of Income Or Comprehensive Income Extensible Enumeration Not Disclosed Flag ImpairmentLongLivedAssetHeldForUseStatementOfIncomeOrComprehensiveIncomeExtensibleEnumerationNotDisclosedFlag	impairment charges on leasehold assets
CY2022	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	0	usd
CY2020	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	0	usd
CY2021	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	0	usd
CY2022Q4	us-gaap	Deposits Negotiable Order Of Withdrawal Now DepositsNegotiableOrderOfWithdrawalNOW	1132290000	usd
CY2022Q4	us-gaap	Weighted Average Rate Domestic Deposit Notice Of Withdrawal WeightedAverageRateDomesticDepositNoticeOfWithdrawal	0.0051
CY2021Q4	us-gaap	Deposits Negotiable Order Of Withdrawal Now DepositsNegotiableOrderOfWithdrawalNOW	1112292000	usd
CY2021Q4	us-gaap	Weighted Average Rate Domestic Deposit Notice Of Withdrawal WeightedAverageRateDomesticDepositNoticeOfWithdrawal	0.0006
CY2022Q4	us-gaap	Noninterest Bearing Deposit Liabilities NoninterestBearingDepositLiabilities	852660000	usd
CY2021Q4	us-gaap	Noninterest Bearing Deposit Liabilities NoninterestBearingDepositLiabilities	898490000	usd
CY2022Q4	nfbk	Deposits Transactions DepositsTransactions	1984950000	usd
CY2022Q4	nfbk	Weighted Average Rate Domestic Deposit Transaction WeightedAverageRateDomesticDepositTransaction	0.0029
CY2021Q4	nfbk	Deposits Transactions DepositsTransactions	2010782000	usd
CY2021Q4	nfbk	Weighted Average Rate Domestic Deposit Transaction WeightedAverageRateDomesticDepositTransaction	0.0003
CY2022Q4	us-gaap	Deposits Money Market Deposits DepositsMoneyMarketDeposits	508067000	usd
CY2022Q4	us-gaap	Weighted Average Rate Domestic Deposit Money Market WeightedAverageRateDomesticDepositMoneyMarket	0.0047
CY2021Q4	us-gaap	Deposits Money Market Deposits DepositsMoneyMarketDeposits	609430000	usd
CY2021Q4	us-gaap	Weighted Average Rate Domestic Deposit Money Market WeightedAverageRateDomesticDepositMoneyMarket	0.0007
CY2022Q4	us-gaap	Interest Bearing Deposit Liabilities InterestBearingDepositLiabilities	917180000	usd
CY2022Q4	nfbk	Weighted Average Interest Rate Of Time Deposits Interest Bearing Deposit Liabilities WeightedAverageInterestRateOfTimeDepositsInterestBearingDepositLiabilities	0.0014
CY2021Q4	us-gaap	Interest Bearing Deposit Liabilities InterestBearingDepositLiabilities	1166761000	usd
CY2021Q4	nfbk	Weighted Average Interest Rate Of Time Deposits Interest Bearing Deposit Liabilities WeightedAverageInterestRateOfTimeDepositsInterestBearingDepositLiabilities	0.0010
CY2022Q4	us-gaap	Deposits Savings Deposits DepositsSavingsDeposits	1425247000	usd
CY2022Q4	us-gaap	Weighted Average Rate Domestic Deposit Savings WeightedAverageRateDomesticDepositSavings	0.0026
CY2021Q4	us-gaap	Deposits Savings Deposits DepositsSavingsDeposits	1776191000	usd
CY2021Q4	us-gaap	Weighted Average Rate Domestic Deposit Savings WeightedAverageRateDomesticDepositSavings	0.0009
CY2022Q4	us-gaap	Time Deposits Less Than100000 TimeDepositsLessThan100000	525944000	usd
CY2022Q4	nfbk	Weighted Average Interest Rateof Time Deposits Less Than100000 WeightedAverageInterestRateofTimeDepositsLessThan100000	0.0306
CY2021Q4	us-gaap	Time Deposits Less Than100000 TimeDepositsLessThan100000	154320000	usd
CY2021Q4	nfbk	Weighted Average Interest Rateof Time Deposits Less Than100000 WeightedAverageInterestRateofTimeDepositsLessThan100000	0.0059
CY2022Q4	us-gaap	Time Deposits100000 Or More TimeDeposits100000OrMore	214078000	usd
CY2022Q4	us-gaap	Weighted Average Interest Rate Of Time Deposits100000 Or More WeightedAverageInterestRateOfTimeDeposits100000OrMore	0.0117
CY2021Q4	us-gaap	Time Deposits100000 Or More TimeDeposits100000OrMore	228041000	usd
CY2021Q4	us-gaap	Weighted Average Interest Rate Of Time Deposits100000 Or More WeightedAverageInterestRateOfTimeDeposits100000OrMore	0.0075
CY2022Q4	us-gaap	Time Deposits TimeDeposits	740022000	usd
CY2022Q4	us-gaap	Weighted Average Rate Domestic Deposit Time Deposits WeightedAverageRateDomesticDepositTimeDeposits	0.0251
CY2021Q4	us-gaap	Time Deposits TimeDeposits	382361000	usd
CY2021Q4	us-gaap	Weighted Average Rate Domestic Deposit Time Deposits WeightedAverageRateDomesticDepositTimeDeposits	0.0069
CY2022Q4	us-gaap	Deposits Deposits	4150219000	usd
CY2022Q4	us-gaap	Weighted Average Rate Domestic Deposit WeightedAverageRateDomesticDeposit	0.0068
CY2021Q4	us-gaap	Deposits Deposits	4169334000	usd
CY2021Q4	us-gaap	Weighted Average Rate Domestic Deposit WeightedAverageRateDomesticDeposit	0.0012
CY2022Q4	us-gaap	Time Deposit Maturities Year One TimeDepositMaturitiesYearOne	685323000	usd
CY2022Q4	us-gaap	Time Deposit Maturities Year Two TimeDepositMaturitiesYearTwo	28653000	usd
CY2022Q4	us-gaap	Time Deposit Maturities Year Three TimeDepositMaturitiesYearThree	14663000	usd
CY2022Q4	us-gaap	Time Deposit Maturities Year Four TimeDepositMaturitiesYearFour	3968000	usd
CY2022Q4	us-gaap	Time Deposit Maturities Year Five TimeDepositMaturitiesYearFive	7415000	usd
CY2022Q4	us-gaap	Time Deposits TimeDeposits	740022000	usd
CY2022	nfbk	Interest Expense Domestic Deposit Liabilities Transaction InterestExpenseDomesticDepositLiabilitiesTransaction	1759000	usd
CY2021	nfbk	Interest Expense Domestic Deposit Liabilities Transaction InterestExpenseDomesticDepositLiabilitiesTransaction	805000	usd
CY2020	nfbk	Interest Expense Domestic Deposit Liabilities Transaction InterestExpenseDomesticDepositLiabilitiesTransaction	2372000	usd
CY2022	nfbk	Interest Expense Domestic Deposit Liabilities Savings And Money Market InterestExpenseDomesticDepositLiabilitiesSavingsAndMoneyMarket	1851000	usd
CY2021	nfbk	Interest Expense Domestic Deposit Liabilities Savings And Money Market InterestExpenseDomesticDepositLiabilitiesSavingsAndMoneyMarket	2226000	usd
CY2020	nfbk	Interest Expense Domestic Deposit Liabilities Savings And Money Market InterestExpenseDomesticDepositLiabilitiesSavingsAndMoneyMarket	7869000	usd
CY2022	us-gaap	Interest Expense Domestic Deposit Liabilities Certificates Of Deposit InterestExpenseDomesticDepositLiabilitiesCertificatesOfDeposit	6679000	usd
CY2021	us-gaap	Interest Expense Domestic Deposit Liabilities Certificates Of Deposit InterestExpenseDomesticDepositLiabilitiesCertificatesOfDeposit	3176000	usd
CY2020	us-gaap	Interest Expense Domestic Deposit Liabilities Certificates Of Deposit InterestExpenseDomesticDepositLiabilitiesCertificatesOfDeposit	14989000	usd
CY2022	us-gaap	Interest Expense Deposits InterestExpenseDeposits	10289000	usd
CY2021	us-gaap	Interest Expense Deposits InterestExpenseDeposits	6207000	usd
CY2020	us-gaap	Interest Expense Deposits InterestExpenseDeposits	25230000	usd
CY2022Q4	nfbk	Repurchase Agreement Included In Overnight Accounts RepurchaseAgreementIncludedInOvernightAccounts	25000000	usd
CY2021Q4	nfbk	Repurchase Agreement Included In Overnight Accounts RepurchaseAgreementIncludedInOvernightAccounts	50000000	usd
CY2022Q4	us-gaap	Federal Home Loan Bank Advances Long Term FederalHomeLoanBankAdvancesLongTerm	547000000	usd
CY2021Q4	us-gaap	Federal Home Loan Bank Advances Long Term FederalHomeLoanBankAdvancesLongTerm	365000000	usd
CY2022Q4	nfbk	Long Term Debt Floating Rate Advances And Other Interest Bearing Liabilities LongTermDebtFloatingRateAdvancesAndOtherInterestBearingLiabilities	11859000	usd
CY2021Q4	nfbk	Long Term Debt Floating Rate Advances And Other Interest Bearing Liabilities LongTermDebtFloatingRateAdvancesAndOtherInterestBearingLiabilities	6755000	usd
CY2022Q4	us-gaap	Long Term Debt LongTermDebt	583859000	usd
CY2021Q4	us-gaap	Long Term Debt LongTermDebt	421755000	usd
CY2022Q4	nfbk	Overnight Line Of Credit OvernightLineOfCredit	177000000	usd
CY2022Q4	nfbk	Additional Funding Federal Home Loan Bank Advances Long Term AdditionalFundingFederalHomeLoanBankAdvancesLongTerm	1930000000	usd
CY2022Q4	nfbk	Unencumbered Securities UnencumberedSecurities	359900000	usd
CY2022Q4	nfbk	Multifamily Loans Held As Collateral By Federal Home Loan Bank MultifamilyLoansHeldAsCollateralByFederalHomeLoanBank	1570000000	usd
CY2022Q2	us-gaap	Subordinated Debt SubordinatedDebt	62000000	usd
CY2022	us-gaap	Subordinated Borrowing Interest Rate SubordinatedBorrowingInterestRate	0.0500
CY2022Q2	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	1100000	usd
CY2022Q4	us-gaap	Accumulated Amortization Deferred Finance Costs AccumulatedAmortizationDeferredFinanceCosts	112000	usd
CY2022	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	15784000	usd
CY2021	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	15313000	usd
CY2020	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	11270000	usd
CY2022	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-233000	usd
CY2021	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	3107000	usd
CY2020	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-2391000	usd
CY2022	us-gaap	Federal Income Tax Expense Benefit Continuing Operations FederalIncomeTaxExpenseBenefitContinuingOperations	15551000	usd
CY2021	us-gaap	Federal Income Tax Expense Benefit Continuing Operations FederalIncomeTaxExpenseBenefitContinuingOperations	18420000	usd
CY2020	us-gaap	Federal Income Tax Expense Benefit Continuing Operations FederalIncomeTaxExpenseBenefitContinuingOperations	8879000	usd
CY2022	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	8581000	usd
CY2021	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	8001000	usd
CY2020	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	4825000	usd
CY2022	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-392000	usd
CY2021	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	52000	usd
CY2020	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-667000	usd
CY2022	us-gaap	State And Local Income Tax Expense Benefit Continuing Operations StateAndLocalIncomeTaxExpenseBenefitContinuingOperations	8189000	usd
CY2021	us-gaap	State And Local Income Tax Expense Benefit Continuing Operations StateAndLocalIncomeTaxExpenseBenefitContinuingOperations	8053000	usd
CY2020	us-gaap	State And Local Income Tax Expense Benefit Continuing Operations StateAndLocalIncomeTaxExpenseBenefitContinuingOperations	4158000	usd
CY2022	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	23740000	usd
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	26473000	usd
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	13037000	usd
CY2022	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	17820000	usd
CY2021	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	20397000	usd
CY2020	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	10505000	usd
CY2022	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2021	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2020	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2022	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	6469000	usd
CY2021	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	6362000	usd
CY2020	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	3285000	usd
CY2022	nfbk	Effective Income Tax Rate Reconciliation Tax Exempt Income Life Insurance Amount EffectiveIncomeTaxRateReconciliationTaxExemptIncomeLifeInsuranceAmount	717000	usd
CY2021	nfbk	Effective Income Tax Rate Reconciliation Tax Exempt Income Life Insurance Amount EffectiveIncomeTaxRateReconciliationTaxExemptIncomeLifeInsuranceAmount	862000	usd
CY2020	nfbk	Effective Income Tax Rate Reconciliation Tax Exempt Income Life Insurance Amount EffectiveIncomeTaxRateReconciliationTaxExemptIncomeLifeInsuranceAmount	793000	usd
CY2022	nfbk	Income Tax Rate Reconciliation Deduction Employee Stock Ownership Plan Fair Market Value Adjustment Amount IncomeTaxRateReconciliationDeductionEmployeeStockOwnershipPlanFairMarketValueAdjustmentAmount	69000	usd
CY2021	nfbk	Income Tax Rate Reconciliation Deduction Employee Stock Ownership Plan Fair Market Value Adjustment Amount IncomeTaxRateReconciliationDeductionEmployeeStockOwnershipPlanFairMarketValueAdjustmentAmount	102000	usd
CY2020	nfbk	Income Tax Rate Reconciliation Deduction Employee Stock Ownership Plan Fair Market Value Adjustment Amount IncomeTaxRateReconciliationDeductionEmployeeStockOwnershipPlanFairMarketValueAdjustmentAmount	42000	usd
CY2022	us-gaap	Income Tax Reconciliation Nondeductible Expense Share Based Compensation Cost IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost	0	usd
CY2021	us-gaap	Income Tax Reconciliation Nondeductible Expense Share Based Compensation Cost IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost	6000	usd
CY2020	us-gaap	Income Tax Reconciliation Nondeductible Expense Share Based Compensation Cost IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost	18000	usd
CY2022	nfbk	Income Tax Reconciliation Acquisition Related Costs IncomeTaxReconciliationAcquisitionRelatedCosts	0	usd
CY2021	nfbk	Income Tax Reconciliation Acquisition Related Costs IncomeTaxReconciliationAcquisitionRelatedCosts	0	usd
CY2020	nfbk	Income Tax Reconciliation Acquisition Related Costs IncomeTaxReconciliationAcquisitionRelatedCosts	-147000	usd
CY2022	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	99000	usd
CY2021	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	468000	usd
CY2020	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-167000	usd
CY2022	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	23740000	usd
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	26473000	usd
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	13037000	usd
CY2022Q4	nfbk	Deferred Tax Assets Allowance For Credit Losses DeferredTaxAssetsAllowanceForCreditLosses	12202000	usd
CY2021Q4	nfbk	Deferred Tax Assets Allowance For Credit Losses DeferredTaxAssetsAllowanceForCreditLosses	11057000	usd
CY2022Q4	nfbk	Deferred Tax Assets Capital Leases DeferredTaxAssetsCapitalLeases		usd
CY2021Q4	nfbk	Deferred Tax Assets Capital Leases DeferredTaxAssetsCapitalLeases		usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits	2958000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits	3145000	usd
CY2022Q4	nfbk	Deferred Tax Assets Accrued Salaries And Benefits And Other DeferredTaxAssetsAccruedSalariesAndBenefitsAndOther	1610000	usd
CY2021Q4	nfbk	Deferred Tax Assets Accrued Salaries And Benefits And Other DeferredTaxAssetsAccruedSalariesAndBenefitsAndOther	1338000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Postretirement Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits	313000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Postretirement Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits	354000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	2091000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	2051000	usd
CY2022Q4	nfbk	Deferred Tax Assets Straight Line Rent Adjustments DeferredTaxAssetsStraightLineRentAdjustments	1608000	usd
CY2021Q4	nfbk	Deferred Tax Assets Straight Line Rent Adjustments DeferredTaxAssetsStraightLineRentAdjustments	1713000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Asset Retirement Obligations DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAssetRetirementObligations	47000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Asset Retirement Obligations DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAssetRetirementObligations	68000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Returns And Allowances DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReturnsAndAllowances	681000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Returns And Allowances DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReturnsAndAllowances	620000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	231000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	537000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	633000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	645000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	323000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	317000	usd
CY2022Q4	nfbk	Deferred Tax Assets Depreciation DeferredTaxAssetsDepreciation	3552000	usd
CY2021Q4	nfbk	Deferred Tax Assets Depreciation DeferredTaxAssetsDepreciation	3229000	usd
CY2022Q4	nfbk	Deferred Tax Assets Related To Fair Value Adjustments On Business Acquisitions DeferredTaxAssetsRelatedToFairValueAdjustmentsOnBusinessAcquisitions	1057000	usd
CY2021Q4	nfbk	Deferred Tax Assets Related To Fair Value Adjustments On Business Acquisitions DeferredTaxAssetsRelatedToFairValueAdjustmentsOnBusinessAcquisitions	1440000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Pensions DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPensions	130000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Pensions DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPensions	139000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Unrealized Losses On Availablefor Sale Securities Gross DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross	18875000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Unrealized Losses On Availablefor Sale Securities Gross DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross	0	usd
CY2020	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	0	usd
CY2022Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	87000	usd
CY2021Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	141000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	46311000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	26653000	usd
CY2022Q4	us-gaap	Deferred Tax Liabilities Unrealized Gains On Trading Securities DeferredTaxLiabilitiesUnrealizedGainsOnTradingSecurities	0	usd
CY2021Q4	us-gaap	Deferred Tax Liabilities Unrealized Gains On Trading Securities DeferredTaxLiabilitiesUnrealizedGainsOnTradingSecurities	761000	usd
CY2022Q4	nfbk	Deferred Tax Liabilities Unrealized Actuarial Gains On Post Retirement Benefits DeferredTaxLiabilitiesUnrealizedActuarialGainsOnPostRetirementBenefits	65000	usd
CY2021Q4	nfbk	Deferred Tax Liabilities Unrealized Actuarial Gains On Post Retirement Benefits DeferredTaxLiabilitiesUnrealizedActuarialGainsOnPostRetirementBenefits	15000	usd
CY2022Q4	nfbk	Deferred Tax Liabilities Adjustment Of Investment Securities DeferredTaxLiabilitiesAdjustmentOfInvestmentSecurities	280000	usd
CY2021Q4	nfbk	Deferred Tax Liabilities Adjustment Of Investment Securities DeferredTaxLiabilitiesAdjustmentOfInvestmentSecurities	580000	usd
CY2022Q4	nfbk	Deferred Tax Liabilities Adjustment Of Deposit Liabilities DeferredTaxLiabilitiesAdjustmentOfDepositLiabilities	32000	usd
CY2021Q4	nfbk	Deferred Tax Liabilities Adjustment Of Deposit Liabilities DeferredTaxLiabilitiesAdjustmentOfDepositLiabilities	28000	usd
CY2022Q4	nfbk	Deferred Tax Liability Deferred Loan Fees DeferredTaxLiabilityDeferredLoanFees	2553000	usd
CY2021Q4	nfbk	Deferred Tax Liability Deferred Loan Fees DeferredTaxLiabilityDeferredLoanFees	2010000	usd
CY2022Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	20000	usd
CY2021Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	23000	usd
CY2022Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	2950000	usd
CY2021Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	3417000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	43361000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	23236000	usd
CY2021	nfbk	Amount Of Bad Debts Reserved For In Current Year AmountOfBadDebtsReservedForInCurrentYear	5900000	usd
CY2022	nfbk	Amount Of Bad Debts Reserved For In Current Year AmountOfBadDebtsReservedForInCurrentYear	5900000	usd
CY2021Q4	nfbk	Federal Tax Bad Debt Deferred Tax Liability FederalTaxBadDebtDeferredTaxLiability	2800000	usd
CY2022Q4	nfbk	Federal Tax Bad Debt Deferred Tax Liability FederalTaxBadDebtDeferredTaxLiability	2800000	usd
CY2021Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	141000	usd
CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	157000	usd
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	190000	usd
CY2022	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	31000	usd
CY2021	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	125000	usd
CY2020	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	33000	usd
CY2022	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	23000	usd
CY2021	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	109000	usd
CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	157000	usd
CY2022	nfbk	Defined Contribution Plan Requisite Service Period DefinedContributionPlanRequisiteServicePeriod	P3M
CY2022	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent Of Match DefinedContributionPlanEmployerMatchingContributionPercentOfMatch	0.25
CY2022	nfbk	Percentage Contribution From Employees First Base Compensation PercentageContributionFromEmployeesFirstBaseCompensation	0.06
CY2022	nfbk	Defined Contribution Plan Vesting Period DefinedContributionPlanVestingPeriod	P3Y
CY2022	nfbk	Defined Contribution Plan Periodof Participationto Trigger Increasein Employee Contribution Percentage DefinedContributionPlanPeriodofParticipationtoTriggerIncreaseinEmployeeContributionPercentage	P3Y
CY2022	nfbk	Percentage Contribution From Employees First Base Compensation PercentageContributionFromEmployeesFirstBaseCompensation	0.06
CY2022	nfbk	Defined Contribution Plan Requisite Service Periodto Become Fully Vested DefinedContributionPlanRequisiteServicePeriodtoBecomeFullyVested	P5Y
CY2022	us-gaap	Defined Contribution Plan Employer Discretionary Contribution Amount DefinedContributionPlanEmployerDiscretionaryContributionAmount	553000	usd
CY2021	us-gaap	Defined Contribution Plan Employer Discretionary Contribution Amount DefinedContributionPlanEmployerDiscretionaryContributionAmount	515000	usd
CY2020	us-gaap	Defined Contribution Plan Employer Discretionary Contribution Amount DefinedContributionPlanEmployerDiscretionaryContributionAmount	508000	usd
CY2022	us-gaap	Employee Stock Ownership Plan Esop Compensation Expense EmployeeStockOwnershipPlanESOPCompensationExpense	1700000	usd
CY2021	us-gaap	Employee Stock Ownership Plan Esop Compensation Expense EmployeeStockOwnershipPlanESOPCompensationExpense	1900000	usd
CY2020	us-gaap	Employee Stock Ownership Plan Esop Compensation Expense EmployeeStockOwnershipPlanESOPCompensationExpense	1400000	usd
CY2022	us-gaap	Defined Benefit Plan Benefit Obligation Benefits Paid DefinedBenefitPlanBenefitObligationBenefitsPaid	81000	usd
CY2022Q4	us-gaap	Defined Benefit Plan Expected Amortization Of Gain Loss Next Fiscal Year DefinedBenefitPlanExpectedAmortizationOfGainLossNextFiscalYear	2000	usd
CY2022Q4	us-gaap	Defined Benefit Plan Expected Amortization Of Prior Service Cost Credit Next Fiscal Year DefinedBenefitPlanExpectedAmortizationOfPriorServiceCostCreditNextFiscalYear	-19000	usd
CY2022Q4	us-gaap	Defined Benefit Plan Ultimate Health Care Cost Trend Rate1 DefinedBenefitPlanUltimateHealthCareCostTrendRate1	0.0875
CY2022	nfbk	Defined Benefit Plan Ultimate Health Care Cost Trend Rate Reduction DefinedBenefitPlanUltimateHealthCareCostTrendRateReduction	0.0050
CY2022Q4	us-gaap	Defined Benefit Plan Health Care Cost Trend Rate Assumed Next Fiscal Year DefinedBenefitPlanHealthCareCostTrendRateAssumedNextFiscalYear	0.0475
CY2021	us-gaap	Defined Benefit Plan Benefit Obligation Benefits Paid DefinedBenefitPlanBenefitObligationBenefitsPaid	99000	usd
CY2020	us-gaap	Defined Benefit Plan Benefit Obligation Benefits Paid DefinedBenefitPlanBenefitObligationBenefitsPaid	97000	usd
CY2022Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Next Twelve Months DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths	80000	usd
CY2022Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Two DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo	78000	usd
CY2022Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Three DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree	76000	usd
CY2022Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Four DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour	73000	usd
CY2022Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Five DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive	70000	usd
CY2022Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Five Fiscal Years Thereafter DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter	299000	usd
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2022	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	1800000	usd
CY2021	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	994000	usd
CY2020	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	1400000	usd
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	13.95
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P2Y11M12D
CY2022	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	187153	shares
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
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	50169	shares
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Options Forfeited Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue
CY2021	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	13.62
CY2021	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	394045	shares
CY2021	nfbk	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageGrantDateFairValue	3.96
CY2021	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	13.90
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	1769979	shares
CY2021Q4	nfbk	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageGrantDateFairValue	4.02
CY2022	nfbk	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageGrantDateFairValue	3.92
CY2022	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	13.23
CY2022Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	1582826	shares
CY2022Q4	nfbk	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageGrantDateFairValue	4.03
CY2022Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	14.04
CY2022	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P2Y3D
CY2022Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	1582826	shares
CY2022Q4	nfbk	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageGrantDateFairValue	4.03
CY2022Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	14.04
CY2022	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1	P2Y3D
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
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	176930	shares
CY2021	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	12.36
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	42470	shares
CY2021	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	16.06
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	15626	shares
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	13.80
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	222844	shares
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	13.21
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	181908	shares
CY2022	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	15.78
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	62836	shares
CY2022	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	12.87
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	20415	shares
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	14.34
CY2022Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	321501	shares
CY2022Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	14.66
CY2022	nfbk	Guaranteed Lease Residual Values Period GuaranteedLeaseResidualValuesPeriod	P1Y
CY2022Q4	nfbk	Commitments To Extend Credit Allowance For Estimated Losses CommitmentsToExtendCreditAllowanceForEstimatedLosses	791000	usd
CY2021Q4	nfbk	Commitments To Extend Credit Allowance For Estimated Losses CommitmentsToExtendCreditAllowanceForEstimatedLosses	1900000	usd
CY2022	nfbk	Agreement Term AgreementTerm	P3Y
CY2022	nfbk	Agreement Term AgreementTerm	P3Y
CY2022Q4	nfbk	Tier One Common Capital Requiredfor Capital Adequacyto Risk Weighted Assets TierOneCommonCapitalRequiredforCapitalAdequacytoRiskWeightedAssets	0.045
CY2022Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.060
CY2022Q4	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.080
CY2022Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.040
CY2022Q4	us-gaap	Tier One Leverage Capital Required To Be Well Capitalized To Average Assets TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets	0.050
CY2022Q4	nfbk	Tier One Common Capital Requiredtobe Well Capitalizedto Risk Weighted Assets TierOneCommonCapitalRequiredtobeWellCapitalizedtoRiskWeightedAssets	0.065
CY2022Q4	us-gaap	Tier One Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets	0.080
CY2022Q4	us-gaap	Capital Required To Be Well Capitalized To Risk Weighted Assets CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets	0.100
CY2022Q4	nfbk	Tier One Common Capital Requiredfor Capital Adequacyto Risk Weighted Assets TierOneCommonCapitalRequiredforCapitalAdequacytoRiskWeightedAssets	0.045
CY2022Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.06
CY2022Q4	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.08
CY2022Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.04
CY2022Q4	nfbk	Tier One Risk Based Capital Requiredfor Capital Adequacyto Risk Weighted Assets Higher Risk Weight TierOneRiskBasedCapitalRequiredforCapitalAdequacytoRiskWeightedAssetsHigherRiskWeight	0.025
CY2022Q4	nfbk	Banking Regulation Community Bank Leverage Ratio Actual BankingRegulationCommunityBankLeverageRatioActual	708430000	usd
CY2022Q4	nfbk	Banking Regulation Community Bank Leverage Ratio Capital Ratio Actual BankingRegulationCommunityBankLeverageRatioCapitalRatioActual	0.1265
CY2022Q4	nfbk	Banking Regulation Community Bank Leverage Ratio Capital Adequacy Minimum Amount BankingRegulationCommunityBankLeverageRatioCapitalAdequacyMinimumAmount	503977000	usd
CY2022Q4	nfbk	Banking Regulation Community Bank Leverage Ratio Capital Adequacy Minimum BankingRegulationCommunityBankLeverageRatioCapitalAdequacyMinimum	0.0900
CY2022Q4	nfbk	Banking Regulation Community Bank Leverage Ratio Well Capitalized Minimum Amount BankingRegulationCommunityBankLeverageRatioWellCapitalizedMinimumAmount	503977000	usd
CY2022Q4	nfbk	Banking Regulation Community Bank Leverage Ratio Well Capitalized Minimum BankingRegulationCommunityBankLeverageRatioWellCapitalizedMinimum	0.0900
CY2021Q4	nfbk	Tier One Common Equity TierOneCommonEquity	696368000	usd
CY2021Q4	nfbk	Tier One Common Capitalto Risk Weighted Assets TierOneCommonCapitaltoRiskWeightedAssets	0.1293
CY2021Q4	nfbk	Tier One Common Equity Requiredfor Capital Adequacy TierOneCommonEquityRequiredforCapitalAdequacy	457751000	usd
CY2021Q4	nfbk	Tier One Common Capital Requiredfor Capital Adequacyto Risk Weighted Assets TierOneCommonCapitalRequiredforCapitalAdequacytoRiskWeightedAssets	0.0850
CY2021Q4	nfbk	Tier One Common Equity Requiredtobe Well Capitalized TierOneCommonEquityRequiredtobeWellCapitalized	457751000	usd
CY2021Q4	nfbk	Tier One Common Capital Requiredtobe Well Capitalizedto Risk Weighted Assets TierOneCommonCapitalRequiredtobeWellCapitalizedtoRiskWeightedAssets	0.0850
CY2022Q4	nfbk	Investment Owned At Net Asset Value InvestmentOwnedAtNetAssetValue	10100000	usd
CY2021Q4	nfbk	Investment Owned At Net Asset Value InvestmentOwnedAtNetAssetValue	5000000	usd
CY2022Q4	us-gaap	Loans Receivable Fair Value Disclosure LoansReceivableFairValueDisclosure	4640000	usd
CY2021Q4	us-gaap	Loans Receivable Fair Value Disclosure LoansReceivableFairValueDisclosure	3807000	usd
CY2021Q4	nfbk	Other Real Estate Owned Fair Value Disclosure OtherRealEstateOwnedFairValueDisclosure	100000	usd
CY2022Q4	nfbk	Principal Amount Outstanding Of Impaired Loans Heldfor Investment And Heldfor Sale PrincipalAmountOutstandingOfImpairedLoansHeldforInvestmentAndHeldforSale	6700000	usd
CY2021Q4	nfbk	Principal Amount Outstanding Of Impaired Loans Heldfor Investment And Heldfor Sale PrincipalAmountOutstandingOfImpairedLoansHeldforInvestmentAndHeldforSale	5800000	usd
CY2022Q4	nfbk	Estimated Fair Value Of Impaired Loans Held For Investment EstimatedFairValueOfImpairedLoansHeldForInvestment	4600000	usd
CY2021Q4	nfbk	Estimated Fair Value Of Impaired Loans Held For Investment EstimatedFairValueOfImpairedLoansHeldForInvestment	3800000	usd
CY2022	us-gaap	Asset Impairment Charges AssetImpairmentCharges	8000	usd
CY2021	us-gaap	Asset Impairment Charges AssetImpairmentCharges	43000	usd
CY2022	nfbk	Impaired Financing Receivables Charge Off ImpairedFinancingReceivablesChargeOff	838000	usd
CY2021	nfbk	Impaired Financing Receivables Charge Off ImpairedFinancingReceivablesChargeOff	2800000	usd
CY2022Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	0	usd
CY2021Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	100000	usd
CY2022Q4	nfbk	Investment Owned At Net Asset Value InvestmentOwnedAtNetAssetValue	10100000	usd
CY2021	nfbk	Derivative Asset Statement Of Financial Position Extensible Enumeration Not Disclosed Flag DerivativeAssetStatementOfFinancialPositionExtensibleEnumerationNotDisclosedFlag	Derivative assets
CY2021	nfbk	Derivative Liability Statement Of Financial Position Extensible Enumeration Not Disclosed Flag DerivativeLiabilityStatementOfFinancialPositionExtensibleEnumerationNotDisclosedFlag	Derivative liabilities
CY2021Q4	nfbk	Investment Owned At Net Asset Value InvestmentOwnedAtNetAssetValue	5000000	usd
CY2022	us-gaap	Net Income Loss NetIncomeLoss	61119000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	70654000	usd
CY2020	us-gaap	Net Income Loss NetIncomeLoss	36988000	usd
CY2022	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	46234122	shares
CY2022	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	46234122	shares
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	48416495	shares
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	48721504	shares
CY2022	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	203997	shares
CY2021	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	337768	shares
CY2020	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	64459	shares
CY2022	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	46438119	shares
CY2022	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	46438119	shares
CY2021	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	48754263	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	48785963	shares
CY2022	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.32
CY2022	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.32
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.46
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.76
CY2022	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.32
CY2022	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.32
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.45
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.76
CY2022	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	756765	shares
CY2021	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	323466	shares
CY2020	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1972136	shares
CY2022	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	5705000	usd
CY2021	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	5394000	usd
CY2020	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	3967000	usd
CY2022	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	3414000	usd
CY2021	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	4103000	usd
CY2020	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	3774000	usd
CY2022	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	279000	usd
CY2021	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	1495000	usd
CY2020	us-gaap	Debt Securities Available For Sale Gain Loss DebtSecuritiesAvailableForSaleGainLoss	327000	usd
CY2022	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	-2206000	usd
CY2021	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	1703000	usd
CY2020	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	1601000	usd
CY2022	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	453000	usd
CY2021	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	1401000	usd
CY2020	us-gaap	Gain Loss On Sales Of Loans Net GainLossOnSalesOfLoansNet	665000	usd
CY2022	us-gaap	Revenue Not From Contract With Customer Other RevenueNotFromContractWithCustomerOther	338000	usd
CY2021	us-gaap	Revenue Not From Contract With Customer Other RevenueNotFromContractWithCustomerOther	357000	usd
CY2020	us-gaap	Revenue Not From Contract With Customer Other RevenueNotFromContractWithCustomerOther	1138000	usd
CY2022	us-gaap	Noninterest Income NoninterestIncome	7983000	usd
CY2021	us-gaap	Noninterest Income NoninterestIncome	14453000	usd
CY2020	us-gaap	Noninterest Income NoninterestIncome	11472000	usd
CY2022Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	34300000	usd
CY2022Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	39800000	usd
CY2021Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	33900000	usd
CY2021Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	39900000	usd
CY2022	us-gaap	Operating Lease Cost OperatingLeaseCost	6006000	usd
CY2021	us-gaap	Operating Lease Cost OperatingLeaseCost	5797000	usd
CY2020	us-gaap	Operating Lease Cost OperatingLeaseCost	6160000	usd
CY2022	us-gaap	Variable Lease Cost VariableLeaseCost	3621000	usd
CY2021	us-gaap	Variable Lease Cost VariableLeaseCost	4092000	usd
CY2020	us-gaap	Variable Lease Cost VariableLeaseCost	3276000	usd
CY2022	us-gaap	Lease Cost LeaseCost	9627000	usd
CY2021	us-gaap	Lease Cost LeaseCost	9889000	usd
CY2020	us-gaap	Lease Cost LeaseCost	9436000	usd
CY2022	us-gaap	Operating Lease Payments OperatingLeasePayments	6350000	usd
CY2021	us-gaap	Operating Lease Payments OperatingLeasePayments	6538000	usd
CY2020	us-gaap	Operating Lease Payments OperatingLeasePayments	6490000	usd
CY2022	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	4983000	usd
CY2021	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	1596000	usd
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	3568000	usd
CY2022Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P11Y2M19D
CY2021Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P11Y10M2D
CY2020Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P12Y3M10D
CY2022Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0354
CY2021Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0355
CY2020Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0360
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	6490000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	6069000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	5729000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	4967000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	4007000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	22557000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	49819000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	10029000	usd
CY2022Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	39790000	usd
CY2022	us-gaap	Operating Lease Expense OperatingLeaseExpense	6100000	usd
CY2021	us-gaap	Operating Lease Expense OperatingLeaseExpense	5900000	usd
CY2020	us-gaap	Operating Lease Expense OperatingLeaseExpense	8000000	usd
CY2020	nfbk	Operating Lease Accelerated Rent Expense OperatingLeaseAcceleratedRentExpense	1800000	usd
CY2022	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	112000	usd
CY2021	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	0	usd
CY2020	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	0	usd
CY2022	dei	Auditor Name AuditorName	KPMG, LLP
CY2022	dei	Auditor Location AuditorLocation	Short Hills, New Jersey
CY2022	dei	Auditor Firm AuditorFirmId	185

Files In Submission

Name	View Source	Status
nfbk-20221231_def.xml	Edgar Link	unprocessable
nfbk-20221231_cal.xml	Edgar Link	unprocessable
0001493225-23-000055-index-headers.html	Edgar Link	pending
0001493225-23-000055-index.html	Edgar Link	pending
0001493225-23-000055.txt	Edgar Link	pending
0001493225-23-000055-xbrl.zip	Edgar Link	pending
Financial_Report.xlsx	Edgar Link	pending
FilingSummary.xml	Edgar Link	unprocessable
MetaLinks.json	Edgar Link	pending
nfbk-20221231.htm	Edgar Link	pending
nfbk-20221231.xsd	Edgar Link	pending
nfbk-20221231_g1.jpg	Edgar Link	pending
nfbk2022-12x31ex1038nqdcpa.htm	Edgar Link	pending
nfbk2022-12x31ex1039formof.htm	Edgar Link	pending
nfbk20221231ex1037nqdcplan.htm	Edgar Link	pending
nfbk20221231exhibit23.htm	Edgar Link	pending
nfbk20221231exhibit311.htm	Edgar Link	pending
nfbk20221231exhibit312.htm	Edgar Link	pending
nfbk20221231exhibit32.htm	Edgar Link	pending
R1.htm	Edgar Link	pending
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$NFBK
Northfield Bancorp, Inc. Stock $nfbk

2023 Q1 Form 10-K Financial Statement

#000149322523000055 Filed on March 01, 2023

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$NFBK Northfield Bancorp, Inc. Stock $nfbk

2023 Q1 Form 10-K Financial Statement

#000149322523000055 Filed on March 01, 2023

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$NFBK
Northfield Bancorp, Inc. Stock $nfbk