SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
SIGNIFICANT ACCOUNTING POLICIES (Policies)	Sep. 30, 2018
Significant Accounting Policies [Abstract]
Nature of Operations	Nature of Operations Sandy Spring Bancorp (the “Company”), a Maryland corporation, is the bank holding company for Sandy Spring Bank (the “Bank”). Independent and community-oriented, Sandy Spring Bank offers a broad range of commercial banking, retail banking, mortgage and trust services throughout central Maryland, Northern Virginia, and the greater Washington, D.C. market. Through its subsidiaries, Sandy Spring Insurance Corporation and West Financial Services, Inc., Sandy Spring Bank also offers a comprehensive menu of insurance and wealth management services.
Basis of Presentation	Basis of Presentation The accounting and reporting policies of the Company conform to accounting principles generally accepted in the United States of America (“GAAP”) and prevailing practices within the financial services industry for interim financial information and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and notes required for complete financial statements and prevailing practices within the banking industry. The following summary of significant accounting policies of the Company is presented to assist the reader in understanding the financial and other data presented in this report. Operating results for the three and nine months ended September 30, 2018 are not necessarily indicative of the results that may be expected for any future periods or for the year ending December 31, 2018. In the opinion of management, all adjustments (comprising only normal recurring accruals) necessary for a fair presentation of the results of the interim periods have been included. Certain reclassifications have been made to prior period amounts, as necessary, to conform to the current period presentation. The Company has evaluated subsequent events through the date of the issuance of its financial statements. These statements should be read in conjunction with the financial statements and accompanying notes included in the Company’s 2017 Annual Report on Form 10-K as filed with the Securities and Exchange Commission (“SEC”) on February 23, 2018. There have been no significant changes to the Company’s accounting policies as disclosed in the 2017 Annual Report on Form 10-K.
Principles of Consolidation	Principles of Consolidation The unaudited condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiary, Sandy Spring Bank and its subsidiaries, Sandy Spring Insurance Corporation and West Financial Services, Inc. Consolidation has resulted in the elimination of all intercompany accounts and transactions.
Use of Estimates	Use of Estimates The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements, and affect the reported amounts of revenues earned and expenses incurred during the reporting period. Actual results could differ from those estimates. Estimates that could change significantly relate to the provision for loan losses and the related allowance, determination of impaired loans and the related measurement of impairment, potential impairment of goodwill or other intangible assets, valuation of investment securities and the determination of whether impaired securities are other-than-temporarily impaired, valuation of other real estate owned, prepayment rates, valuation of share-based compensation, the assessment that a liability should be recognized with respect to any matters under litigation, the calculation of current and deferred income taxes and the actuarial projections related to pension expense and the related liability.
Cash Flows	Cash Flows For purposes of reporting cash flows, cash and cash equivalents include cash and due from banks, federal funds sold and interest-bearing deposits with banks (items with stated original maturity of three months or less).
Revenue from Contract with Customers [Policy Text Block]	Revenue from Contracts with Customers The Company’s revenue includes net interest income on financial instruments and non-interest income. Specific categories of revenue are presented in the Condensed Consolidated Statements of Income. Most of the Company’s revenue is not within the scope of Accounting Standard Update (ASU) No. 2014-09 – Revenue from Contracts with Customers. For revenue within the scope of ASU 2014-09, the Company provides services to customers and has related performance obligations. The revenue from such services is recognized upon satisfaction of all contractual performance obligations. The following discusses key revenue streams within the scope of the new revenue recognition guidance. Wealth Management Income West Financial Services, Inc., a subsidiary of the Bank, provides comprehensive investment management and financial planning services. Wealth management income is comprised of income for providing trust, estate and investment management services. Trust services include acting as a trustee for corporate or personal trusts. Investment management services include investment management, record-keeping and reporting of security portfolios. Fees for these services are recognized based on a contractually-agreed fixed percentage applied to net assets under management at the end of each reporting period. The Company does not charge/recognize any performance based fees. Insurance Agency Commissions Sandy Spring Insurance, a subsidiary of the Bank, performs the function of an insurance intermediary by introducing the policyholder and insurer and is compensated by a commission fee for placement of an insurance policy. Sandy Spring Insurance does not provide any captive management services or any claim handling services. Commission fees are set as a percentage of the premium for the insurance policy for which the Sandy Spring Insurance is a producer. The Company recognizes revenue when the insurance policy has been contractually agreed to by the insurer and policyholder (at transaction date). Service Charges on Deposit Accounts Service charges on deposit accounts are earned on depository accounts for consumer and commercial account holders and include fees for account and overdraft services. Account services include fees for event-driven services and periodic account maintenance activities. The obligation for event-driven services is satisfied at the time of the event when service is delivered and revenue recognized as earned. Obligation for maintenance activities is satisfied over the course of each month and revenue recognized at month end. Obligation for overdraft services is satisfied at the time of the overdraft and revenue recognized as earned.
Loans Acquired with Deteriorated Credit Quality [Policy Text Block]	Loans Acquired with Deteriorated Credit Quality Acquired loans with evidence of credit deterioration since their origination as of the date of the acquisition are recorded at their initial fair value. Credit deterioration is determined based on the probability of collection of all contractually required principal and interest payments. The historical allowance for loan losses related to the acquired loans is not carried over to the Company’s financial statements. The determination of credit quality deterioration as of the purchase date may include parameters such as past due and non-accrual status, commercial risk ratings, cash flow projections, type of loan and collateral, collateral value and recent loan-to-value ratios or appraised values. For loans acquired with evidence of credit deterioration, the Company determines at the acquisition date the excess of the loan’s contractually required payments over all cash flows expected to be collected as an amount that should not be accreted into interest income (nonaccretable difference). The remaining amount, representing the difference in the expected cash flows of acquired loans and the initial investment in the acquired loans, is accreted into interest income over the remaining life of the loan or pool of loans (accretable yield). Subsequent to the purchase date, increases in expected cash flows over those expected at the purchase date are recognized prospectively as interest income over the remaining life of the loan as an adjustment to the accretable yield. The present value of any decreases in expected cash flows after the purchase date is recognized as an impairment through addition to the valuation allowance.
Pending Accounting Pronouncements	Adopted Accounting Pronouncements The FASB issued Update No. 2014-09, Revenue from Contracts with Customers (Topic 606), in May 2014 that provides accounting guidance for all revenue arising from contracts with customers and affects all entities that enter into contracts to provide goods or services to customers. The guidance also provides for a model for the measurement and recognition of gains and losses on the sale of certain nonfinancial assets, such as property and equipment, including real estate. The Company’s revenue is comprised of net interest income and non-interest income. The guidance does not apply to revenue associated with financial instruments, net interest income, mortgage origination and servicing activities, and gains and losses from securities. Accordingly, the majority of the Company’s revenues have not been affected. The following revenue streams were identified to be in scope of ASC 606: 1) wealth management income; 2) insurance agency commissions; and 3) service charges on deposit accounts. The Company adopted the standard on January 1, 2018 using modified retrospective adoption method. The Company’s accounting policies and revenue recognition principles did not change materially as the principles of ASC 606 are largely consistent with the current revenue recognition practices. The FASB issued Update No. 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income, in February 2018. The guidance permits entities to reclassify from accumulated other comprehensive income (“OCI”) to retained earnings stranded income tax effects resulting from the Tax Cuts and Jobs Act enacted in December 2017. The Company made the election to adopt this guidance during the first quarter of 2018 and reclassified $1.5 million of stranded income tax effects from OCI to retained earnings. The Company made the adjustment between OCI and retained earnings in the Condensed Consolidated Statements of Changes in Stockholders’ Equity as of the beginning of the current reporting period. The FASB issued Update No. 2016-01, Financial Instruments – (Subtopic 825-10): Recognition and Measurement of Financial Assets and Liabilities”, in January 2016. This guidance amends the presentation and accounting for certain financial instruments, including liabilities measured at fair value under fair value option and equity investments. The guidance also updates fair value presentation and disclosure requirements for financial instruments measured at amortized cost. The Company adopted the guidance in the first quarter 2018 with no impact to retained earnings or other comprehensive income. The Company has no investments in marketable equity securities classified as available-for-sale accounted for at fair value. The Company’s marketable equity securities that do not have determinable fair values are measured at cost less any impairment. The Company’s existing accounting policy is consistent with the measurement alternative provided by the guidance. For purposes of disclosing fair values of financial instruments carried at amortized cost, we determined the fair values based on “exit price” as required by the guidance. Pending Accounting Pronouncements The FASB issued Update No. 2017-08, Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities, in March 2017. This guidance is intended to eliminate the current diversity in practice with respect to the amortization period for certain purchased callable debt securities held at a premium. Under current GAAP, entities generally amortize the premium as an adjustment of yield over the contractual life. 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 amendments in this update shorten the amortization period for such callable debt securities held at a premium requiring the premium to be amortized to the earliest call date. This guidance is effective for a public business entity that is a U.S. Securities and Exchange Commission (SEC) filer for its fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. The adoption of this standard is not expected to have a material impact on the Company’s financial position, results of operations or cash flows. The FASB issued Update No. 2017-04, Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment, in January 2017. The objective of this guidance is to simplify an entity’s required test for impairment of goodwill by eliminating Step 2 from the goodwill impairment test. In Step 2 an entity measured a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. In computing the implied fair value of goodwill, an entity had to determine the fair value at the impairment date of its assets and liabilities, including any unrecognized assets and liabilities, following a procedure that would be required in determining the fair value of assets acquired and liabilities assumed in a business combination. Under this Update, an entity should perform its annual or quarterly goodwill impairment test by comparing the fair value of the reporting unit with its carrying amount and record an impairment charge for the excess of the carrying amount over the reporting unit’s fair value. The loss recognized should not exceed the total amount of goodwill allocated to the reporting unit and the entity must consider the income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit when measuring the goodwill impairment loss, if applicable. This guidance is effective for a public business entity that is an SEC filer for its annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. The adoption of this standard is not expected to have a material impact on the Company’s financial position, results of operations or cash flows. The FASB issued Update No. 2016-13, Current Expected Credit Losses (CECL), in June 2016. This guidance changes the impairment model for most financial assets measured at amortized cost and certain other instruments. Entities will be required to use an expected loss model, replacing the incurred loss model that is currently in use. Under the new guidance, an entity will measure all expected credit losses for financial instruments held at the reporting date based on historical experience, current condition and reasonable and supportable forecasts. This will result in earlier recognition of loss allowances in most instances. Credit losses related to available-for-sale debt securities (regardless of whether the impairment is considered to be other-than-temporary) will be measured in a manner similar to the present, except that such losses will be recorded as allowances rather than as reductions in the amortized cost of the related securities. With respect to trade and other receivables, loans, held-to-maturity debt securities, net investments in leases and off-balance-sheet credit exposures, the guidance requires that an entity estimate its lifetime expected credit loss and record an allowance resulting in the net amount expected to be collected to be reflected as the financial asset. Entities are also required to provide significantly more disclosures, including information used to track credit quality by year of origination for most financing receivables. This guidance is effective for public business entities for the first interim or annual period beginning after December 15, 2019. The standard’s provisions will be applied as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. Early adoption by public business entities is permitted for the first interim or annual period beginning after December 15, 2018. The Company assessed the guidance and has identified the available historical loan level information and completed a data gap analysis. The Company is in process of reviewing various calculation methodologies and the approximate impact on the Company’s financial position, results of operations and cash flows. The FASB issued Update No. 2016-02, Leases, in February 2016. From the lessee’s perspective, the new standard establishes a right-of-use (“ROU”) model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement for lessees. The guidance also eliminates the current real estate-specific provision and changes the guidance on sale-leaseback transactions, initial direct costs and lease executory costs. With respect to lessors, the guidance modifies the classification criteria and the accounting for sales-type and direct financing leases. All entities will classify leases to determine how to recognize lease-related revenue and expense. In applying this guidance entities will also need to determine whether an arrangement contains a lease or service agreement. Disclosures are required by lessees and lessors to meet the objective of enabling users of financials statements to assess the amount, timing, and uncertainty of cash flows arising from leases. For public entities, this guidance is effective for the first interim or annual period beginning after December 15, 2018. Early adoption is permitted. The Company assessed this guidance and collected relevant terms for each of its lease agreements. The Company is in process of quantifying the impact on the Company’s financial position, results of operations and cash flows.