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Excludes capital lease obligation ulbi_DebtInstrumentNumberOfMonthlyPayment Debt Instrument, Number of Monthly Payment Represents number of monthly payments for debt instrument. us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet Net assets acquired SWE [Member] Represents information related to SWE Annual Estimated Amortization Expense The annual estimate amortization expense of identifiable intangible assets recognized as of the acquisition date. Communications Systems Segment [Member] Represents the company's communications systems segment. Battery & Energy Products Segment [Member] Represents the company's battery & energy products segment. Distributor Relationships [Member] Represents information pertaining to distributor relationships. us-gaap_StockholdersEquity Total Ultralife Corporation equity Shenzhen Facility [Member] Represents information related to Shenzhen Facility. us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired Payments to Acquire Businesses, Net of Cash Acquired, Total Purchase of SWE, net of cash acquired Class of Stock [Axis] us-gaap_CashAcquiredFromAcquisition Cash Acquired from Acquisition us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities Deferred tax liability, net Long-term debt us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther Other current liabilities us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable Accounts payable Exercisable at September 29, 2019 (in dollars per share) ulbi_DilutiveSecuritiesIncludedInComputationOfEarningsPerShareAmount Dilutive Securities Included in Computation of Earnings Per Share Amount Stock Option Number of employee stock options included in calculation of diluted earnings per share. us-gaap_LongTermPurchaseCommitmentAmount Long-term Purchase Commitment, Amount ulbi_DilutiveSecuritiesIncludedInComputationOfEarningsPerShareAmountRestrictedStock Dilutive Securities Included in Computation of Earnings Per Share Amount Restricted Stock Number of restricted shares included in calculation of diluted earnings per share. us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment Property, equipment and improvements