Significant Accounting Policies (Policies)	3 Months Ended
Mar. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation This quarterly report presents the consolidated financial statements of Lakeland Bancorp, Inc. and its subsidiaries, including Lakeland Bank (“Lakeland”) and the Bank’s wholly owned subsidiaries (collectively, the “Company”). The accounting and reporting policies of the Company conform with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and predominant practices within the banking industry. The Company’s unaudited interim financial statements reflect all adjustments, such as normal recurring accruals that are, in the opinion of management, necessary for the fair presentation of the results of the interim periods. The results of operations for the three months ended March 31, 2019 do not necessarily indicate the results that the Company will achieve for all of 2019. Certain information and footnote disclosures required under U.S. GAAP have been condensed or omitted, as permitted by rules and regulations of the Securities and Exchange Commission. These unaudited interim financial statements should be read in conjunction with the audited consolidated financial statements and accompanying notes that are presented in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018. Certain reclassifications have been made in the consolidated financial statements to conform with current year classifications.
Recent Accounting Pronouncements	In August 2018, the Financial Accounting Standards Board ("FASB") issued an update to improve the effectiveness of fair value measurement disclosures. Among other provisions, the update removes requirements to disclose amounts and reasons of transfers between Level 1 and Level 2 in the fair value hierarchy, and it modifies the disclosures regarding transfers in and out of Level 3 of the fair value hierarchy. The update requires a discussion regarding the change in unrealized gains and losses included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period, and the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. This update will be effective for financial statements issued for fiscal years and interim periods beginning after December 15, 2019. Because the Company does not typically have Level 3 fair value measurements, the update is not expected to have a material impact on the Company's financial statements. In August 2018, the FASB issued an update which aligns the requirements for capitalizing implementation costs in a cloud-computing arrangement service contract with the requirements for capitalizing implementation costs incurred for an internal-use software license. Implementation costs incurred by customers in a cloud computing arrangement are to be deferred and recognized over the term of the arrangement, if those costs would be capitalized by the customer in a software licensing arrangement under the internal-use software guidance. This update will be effective for financial statements issued for fiscal years and interim periods beginning after December 15, 2019. The Company is currently assessing the impact that the guidance will have on its financial statements. In August 2018, the FASB issued an update which changes the disclosure of accounting and reporting requirements related to single-employer defined benefit pension or other postretirement benefit plans. The amendments in the update remove disclosures that are no longer considered cost-beneficial, clarify the specific requirements of disclosures and add disclosure requirements identified as relevant. For calendar-year public companies, the changes will be effective for annual periods, including interim periods within those annual periods, in 2020. Because the Company has minimal pension plans that require calculation of projected benefit obligations or accumulated benefit obligations, the update will not have a material impact on the Company's financial statements. In June 2018, the FASB issued an update expanding earlier guidance on stock compensation to include share-based payments issued to nonemployees for goods and services. Consequently, the accounting for share-based payments to nonemployees and employees will be substantially the same. This update will be effective for financial statements issued for fiscal years and interim periods beginning after December 15, 2018. Earlier adoption was permitted. The adoption of this update did not have a significant impact on the Company's financial statements. In August 2017, the FASB issued an update intended to improve and simplify accounting rules around hedge accounting. Amendments expand and refine hedge accounting for both nonfinancial and financial risk components and align the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements. The amendments in this update also make certain targeted improvements to simplify the application of hedge accounting guidance and ease the administrative burden of hedge documentation requirements and assessing hedge effectiveness. This update will be effective for financial statements issued for fiscal years and interim periods beginning after December 15, 2019. The Company is still evaluating the impact that this guidance will have on its financial statements. In July 2017, the FASB issued guidance which simplifies the accounting for certain financial instruments with down round features, a provision in an equity-linked financial instrument (or embedded feature) that provides a downward adjustment of the current exercise price based on the price of future equity offerings. The provisions of the new guidance related to down rounds are effective for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The adoption of this update did not have a material impact on the Company’s financial statements because the Company does not have any equity-linked financial instruments that have such down round features. In March 2017, the FASB issued an update which shortens the amortization period for certain callable debt securities held at a premium to the earliest call date. Under current GAAP, entities amortize the premium as an adjustment of yield over the contractual life of the instrument even if the holder is certain that the call will be exercised. As a result, upon the exercise of a call on a callable debt security held at a premium, the unamortized premium is recorded as a loss in earnings. The update shortens the amortization period for certain callable debt securities held at a premium and requires the premium be amortized to the earliest call date. This update will be effective for annual and interim periods beginning after December 15, 2018. Entities are required to apply the amendments on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The adoption of this update did not have a material impact on the Company’s financial statements. In January 2017, the FASB issued an update to simplify the test for goodwill impairment. This amendment eliminates Step 2 from the goodwill impairment test. The annual, or interim, goodwill impairment test is performed by comparing the fair value of a reporting unit with its carrying amount. An impairment charge should be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value. This update will be effective for the Company’s financial statements for annual years beginning after December 15, 2019. The adoption of this update is not expected to have a material impact on the Company’s financial statements. In June 2016, the FASB issued an accounting standards update pertaining to the measurement of credit losses on financial instruments. This update requires the measurement of all expected credit losses for financial instruments held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. Financial institutions and other organizations will now use forward-looking information to better inform their credit loss estimates. This update is intended to improve financial reporting by requiring timelier recording of credit losses on loans and other financial instruments held by financial institutions and other organizations. This update will be effective for financial statements issued for fiscal years and interim periods beginning after December 15, 2019. The Company formed a working group under the direction of the Chief Risk Officer that is comprised of individuals from the credit, risk management, finance and project management areas for implementation of this update. In 2018, the Company contracted with a software and advisory service provider to aid in implementation. The software provider has completed configuration of the software platform and the Company has completed initial data preparation for the software. The Company and software provider have begun evaluating results of initial scenario analysis and as a result have been reviewing and fine tuning assumptions in the model. The Company is still developing qualitative adjustments as well as metrics for determination of a reasonable and supportable forecast period. The Company has engaged a third-party firm to conduct a review and validation of our methodology and models. In February 2016, FASB issued accounting guidance that requires all lessees to recognize a lease liability and a right-of-use asset, measured at the present value of the future minimum lease payments, at the lease commencement date. Lessor accounting remains largely unchanged under the new guidance. The guidance is effective for fiscal years beginning after December 15, 2018, including interim reporting periods within that reporting period, with early adoption permitted. A modified retrospective approach must be applied for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The Company retained the services of a software provider to aid in its implementation. In the third quarter of 2018, the FASB issued updates which included targeted improvements to the leasing guidance that is intended to reduce costs and ease implementation of the leases standard. The improvements include an optional transition method to adopt the new leases standard where the entity could initially apply the new leases standard at the adoption date and recognize a cumulative effect adjustment to the opening balance of retained earnings in the period of adoption. Consequently, an entity's reporting for comparative periods presented in the financial statements in which it adopts the new leases standard, will continue to be in accordance with Accounting Standards Codification ("ASC") Topic 840, Leases. An entity that adopts this additional transition method, must provide the required disclosures for all periods that continue to be in accordance with the current ASC 840. The lease update also includes a practical expedient, by class of underlying asset, to not separate nonlease components from the associated lease component and, instead, to account for these components as a single component if the nonlease components otherwise would be accounted for under the new revenue guidance and both of the following conditions are met: 1) the timing and pattern of transfer of the nonlease component(s) and associated lease component are the same, and 2) the lease component, if accounted for separately, would be classified as an operating lease. Management used the optional transition method discussed above and also used the practical expedient to account for non-lease components with the associated lease component as a single component assuming the appropriate conditions are met. The FASB issued further clarification of the standard and addressed implementation and disclosure requirements. With the adoption of this update, the Company recorded an operating lease right-of-use asset of $18.7 million, a corresponding liability of $20.2 million and a cumulative adjustment to retained earnings of $125,000.

In August 2018, the Financial Accounting Standards Board ("FASB") issued an update to improve the effectiveness of fair value measurement disclosures. Among other provisions, the update removes requirements to disclose amounts and reasons of transfers between Level 1 and Level 2 in the fair value hierarchy, and it modifies the disclosures regarding transfers in and out of Level 3 of the fair value hierarchy. The update requires a discussion regarding the change in unrealized gains and losses included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period, and the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. This update will be effective for financial statements issued for fiscal years and interim periods beginning after December 15, 2019. Because the Company does not typically have Level 3 fair value measurements, the update is not expected to have a material impact on the Company's financial statements.

In August 2018, the FASB issued an update which aligns the requirements for capitalizing implementation costs in a cloud-computing arrangement service contract with the requirements for capitalizing implementation costs incurred for an internal-use software license. Implementation costs incurred by customers in a cloud computing arrangement are to be deferred and recognized over the term of the arrangement, if those costs would be capitalized by the customer in a software licensing arrangement under the internal-use software guidance. This update will be effective for financial statements issued for fiscal years and interim periods beginning after December 15, 2019. The Company is currently assessing the impact that the guidance will have on its financial statements.

In August 2018, the FASB issued an update which changes the disclosure of accounting and reporting requirements related to single-employer defined benefit pension or other postretirement benefit plans. The amendments in the update remove disclosures that are no longer considered cost-beneficial, clarify the specific requirements of disclosures and add disclosure requirements identified as relevant. For calendar-year public companies, the changes will be effective for annual periods, including interim periods within those annual periods, in 2020. Because the Company has minimal pension plans that require calculation of projected benefit obligations or accumulated benefit obligations, the update will not have a material impact on the Company's financial statements.

In June 2018, the FASB issued an update expanding earlier guidance on stock compensation to include share-based payments issued to nonemployees for goods and services. Consequently, the accounting for share-based payments to nonemployees and employees will be substantially the same. This update will be effective for financial statements issued for fiscal years and interim periods beginning after December 15, 2018. Earlier adoption was permitted. The adoption of this update did not have a significant impact on the Company's financial statements.

In August 2017, the FASB issued an update intended to improve and simplify accounting rules around hedge accounting. Amendments expand and refine hedge accounting for both nonfinancial and financial risk components and align the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements. The amendments in this update also make certain targeted improvements to simplify the application of hedge accounting guidance and ease the administrative burden of hedge documentation requirements and assessing hedge effectiveness. This update will be effective for financial statements issued for fiscal years and interim periods beginning after December 15, 2019. The Company is still evaluating the impact that this guidance will have on its financial statements.

In July 2017, the FASB issued guidance which simplifies the accounting for certain financial instruments with down round features, a provision in an equity-linked financial instrument (or embedded feature) that provides a downward adjustment of the current exercise price based on the price of future equity offerings. The provisions of the new guidance related to down rounds are effective for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The adoption of this update did not have a material impact on the Company’s financial statements because the Company does not have any equity-linked financial instruments that have such down round features.

In March 2017, the FASB issued an update which shortens the amortization period for certain callable debt securities held at a premium to the earliest call date. Under current GAAP, entities amortize the premium as an adjustment of yield over the contractual life of the instrument even if the holder is certain that the call will be exercised. As a result, upon the exercise of a call on a callable debt security held at a premium, the unamortized premium is recorded as a loss in earnings. The update shortens the amortization period for certain callable debt securities held at a premium and requires the premium be amortized to the earliest call date. This update will be effective for annual and interim periods beginning after December 15, 2018. Entities are required to apply the amendments on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The adoption of this update did not have a material impact on the Company’s financial statements.

In January 2017, the FASB issued an update to simplify the test for goodwill impairment. This amendment eliminates Step 2 from the goodwill impairment test. The annual, or interim, goodwill impairment test is performed by comparing the fair value of a reporting unit with its carrying amount. An impairment charge should be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value. This update will be effective for the Company’s financial statements for annual years beginning after December 15, 2019. The adoption of this update is not expected to have a material impact on the Company’s financial statements.

In June 2016, the FASB issued an accounting standards update pertaining to the measurement of credit losses on financial instruments. This update requires the measurement of all expected credit losses for financial instruments held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. Financial institutions and other organizations will now use forward-looking information to better inform their credit loss estimates. This update is intended to improve financial reporting by requiring timelier recording of credit losses on loans and other financial instruments held by financial institutions and other organizations. This update will be effective for financial statements issued for fiscal years and interim periods beginning after December 15, 2019. The Company formed a working group under the direction of the Chief Risk Officer that is comprised of individuals from the credit, risk management, finance and project management areas for implementation of this update. In 2018, the Company contracted with a software and advisory service provider to aid in implementation. The software provider has completed configuration of the software platform and the Company has completed initial data preparation for the software. The Company and software provider have begun evaluating results of initial scenario analysis and as a result have been reviewing and fine tuning assumptions in the model. The Company is still developing qualitative adjustments as well as metrics for determination of a reasonable and supportable forecast period. The Company has engaged a third-party firm to conduct a review and validation of our methodology and models.

In February 2016, FASB issued accounting guidance that requires all lessees to recognize a lease liability and a right-of-use asset, measured at the present value of the future minimum lease payments, at the lease commencement date. Lessor accounting remains largely unchanged under the new guidance. The guidance is effective for fiscal years beginning after December 15, 2018, including interim reporting periods within that reporting period, with early adoption permitted. A modified retrospective approach must be applied for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The Company retained the services of a software provider to aid in its implementation. In the third quarter of 2018, the FASB issued updates which included targeted improvements to the leasing guidance that is intended to reduce costs and ease implementation of the leases standard. The improvements include an optional transition method to adopt the new leases standard where the entity could initially apply the new leases standard at the adoption date and recognize a cumulative effect adjustment to the opening balance of retained earnings in the period of adoption. Consequently, an entity's reporting for comparative periods presented in the financial statements in which it adopts the new leases standard, will continue to be in accordance with Accounting Standards Codification ("ASC") Topic 840, Leases. An entity that adopts this additional transition method, must provide the required disclosures for all periods that continue to be in accordance with the current ASC 840. The lease update also includes a practical expedient, by class of underlying asset, to not separate nonlease components from the associated lease component and, instead, to account for these components as a single component if the nonlease components otherwise would be accounted for under the new revenue guidance and both of the following conditions are met: 1) the timing and pattern of transfer of the nonlease component(s) and associated lease component are the same, and 2) the lease component, if accounted for separately, would be classified as an operating lease. Management used the optional transition method discussed above and also used the practical expedient to account for non-lease components with the associated lease component as a single component assuming the appropriate conditions are met. The FASB issued further clarification of the standard and addressed implementation and disclosure requirements. With the adoption of this update, the Company recorded an operating lease right-of-use asset of $18.7 million, a corresponding liability of $20.2 million and a cumulative adjustment to retained earnings of $125,000.