Sandy Spring Bancorp (SASR) 10-K 19 Feb 21 2020 FY Annual report Financial data

COVER

COVER - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Feb. 17, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	0-19065
Entity Registrant Name	SANDY SPRING BANCORP, INC.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	52-1532952
Entity Address, Address Line One	17801 Georgia Avenue
Entity Address, City or Town	Olney
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	20832
City Area Code	301
Local Phone Number	774-6400
Title of 12(b) Security	Common Stock, par value $1.00 per share
Trading Symbol	SASR
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 1.1
Entity Common Stock, Shares Outstanding		47,095,833
Documents Incorporated by Reference	Documents Incorporated By Reference Part III: Portions of the definitive proxy statement for the Annual Meeting of Shareholders to be held on April 28, 2021 (the "Proxy Statement").
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Central Index Key	0000824410

CONSOLIDATED STATEMENTS OF COND

CONSOLIDATED STATEMENTS OF CONDITION - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets
Cash and due from banks	$ 93,651	$ 82,469
Federal funds sold	291	208
Interest-bearing deposits with banks	203,061	63,426
Cash and cash equivalents	297,003	146,103
Residential mortgage loans held for sale (at fair value)	78,294	53,701
Investments available-for-sale (at fair value)	1,348,021	1,073,333
Equity securities	65,760	51,803
Total loans	10,400,509	6,705,232
Less: allowance for credit losses	(165,367)	(56,132)
Net loans	10,235,142	6,649,100
Premises and equipment, net	57,720	58,615
Other real estate owned	1,455	1,482
Accrued interest receivable	46,431	23,282
Goodwill	370,223	347,149
Other intangible assets, net	32,521	7,841
Other assets	265,859	216,593
Total assets	12,798,429	8,629,002
Liabilities
Noninterest-bearing deposits	3,325,547	1,892,052
Interest-bearing deposits	6,707,522	4,548,267
Total deposits	10,033,069	6,440,319
Securities sold under retail repurchase agreements and federal funds purchased	543,157	213,605
Advances from FHLB	379,075	513,777
Subordinated debt	227,088	209,406
Total borrowings	1,149,320	936,788
Accrued interest payable and other liabilities	146,085	118,921
Total liabilities	11,328,474	7,496,028
Stockholders' equity
Common stock	47,057	34,970
Additional paid-in capital	846,922	586,622
Retained earnings	557,271	515,714
Accumulated other comprehensive income/ (loss)	18,705	(4,332)
Total stockholders' equity	1,469,955	1,132,974
Total liabilities and stockholders' equity	$ 12,798,429	$ 8,629,002

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF CONDITION - (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	47,056,777	34,970,370
Common stock, shares outstanding (in shares)	47,056,777	34,970,370

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest income:
Interest and fees on loans	$ 393,477	$ 316,550	$ 293,131
Interest on loans held for sale	1,686	1,607	1,245
Interest on deposits with banks	446	2,129	1,304
Interest and dividends on investment securities:
Taxable for federal income taxes	22,136	21,739	20,516
Exempt from federal income taxes	5,814	5,834	7,855
Interest on federal funds sold	1	10	31
Total interest income	423,560	347,869	324,082
Interest expense:
Interest on deposits	41,651	61,681	39,139
Interest on retail repurchase agreements and federal funds purchased	1,965	1,161	1,169
Interest on advances from FHLB	6,593	16,578	21,408
Interest on subordinated debt	10,192	3,141	1,921
Total interest expense	60,401	82,561	63,637
Net interest income	363,159	265,308	260,445
Provision for credit losses	85,669	4,684	9,023
Net interest income after provision for credit losses	277,490	260,624	251,422
Non-interest income:
Investment securities gains	467	77	190
Insurance agency commissions	6,795	6,612	6,158
Income from bank owned life insurance	2,867	3,165	4,327
Other income	9,221	8,780	7,126
Total non-interest income	102,716	71,322	61,049
Non-interest expense:
Salaries and employee benefits	134,471	103,950	96,998
Occupancy expense of premises	21,383	19,470	18,352
Equipment expenses	12,224	10,720	9,335
Marketing	4,281	4,456	3,924
Outside data services	8,759	7,567	6,603
FDIC insurance	4,727	2,260	5,095
Amortization of intangible assets	6,221	1,946	2,162
Merger and acquisition expense	25,174	1,312	11,766
Professional fees and services	7,939	6,978	6,056
Other expenses	30,603	20,426	19,492
Total non-interest expense	255,782	179,085	179,783
Income before income tax expense	124,424	152,861	132,688
Income tax expense	27,471	36,428	31,824
Net income	$ 96,953	$ 116,433	$ 100,864
Net income per common share amounts:
Basic net income per common share (in dollars per share)	$ 2.19	$ 3.25	$ 2.82
Diluted net income per common share (in dollars per share)	2.18	3.25	2.82
Dividends declared per share (in dollars per share)	$ 1.20	$ 1.18	$ 1.10
Service charges on deposit accounts
Non-interest income:
Fees and commissions, mortgage banking and servicing	$ 7,066	$ 9,692	$ 9,324
Mortgage banking activities
Non-interest income:
Fees and commissions, mortgage banking and servicing	40,058	14,711	7,073
Wealth management income
Non-interest income:
Fees and commissions, mortgage banking and servicing	30,570	22,669	21,284
Bank card fees
Non-interest income:
Fees and commissions, mortgage banking and servicing	$ 5,672	$ 5,616	$ 5,567

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 96,953	$ 116,433	$ 100,864
Investments available-for-sale:
Net change in unrealized gains/ (losses) on investments available-for-sale	32,950	14,429	(9,925)
Related income tax expense/ (benefit)	(8,428)	(3,742)	2,600
Net investment gains reclassified into earnings	(467)	(77)	(190)
Related income tax expense	120	20	50
Net effect on other comprehensive income/ (loss)	24,175	10,630	(7,465)
Defined benefit pension plan:
Net change of unrealized (gain)/ loss	(1,542)	1,175	135
Related income tax expense/ (benefit)	404	(383)	(90)
Net effect on other comprehensive income/ (loss)	(1,138)	792	45
Total other comprehensive income/ (loss)	23,037	11,422	(7,420)
Comprehensive income	$ 119,990	$ 127,855	$ 93,444

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Transition impact of adopting ASC 326	Common Stock	Additional Paid-In Capital	Retained Earnings	Retained EarningsTransition impact of adopting ASC 326	Accumulated Other Comprehensive Income/ (Loss)
Balance at beginning of period at Dec. 31, 2017	$ 563,816		$ 23,996	$ 168,188	$ 378,489		$ (6,857)
Net income	100,864				100,864
Other comprehensive loss, net of tax	(7,420)						(7,420)
Total other comprehensive income	93,444
Common stock dividends	(39,277)				(39,277)
Stock compensation expense	2,645			2,645
Acquisition	441		21	420
Stock option plan	446,640		11,446	435,194
Employee stock purchase plan	954		29	925
Restricted stock, net	(760)		39	(799)
Reclassification of tax effects from other comprehensive income/ (loss)	0				1,477		(1,477)
Balance at end of period at Dec. 31, 2018	1,067,903		35,531	606,573	441,553		(15,754)
Net income	116,433				116,433
Other comprehensive loss, net of tax	11,422						11,422
Total other comprehensive income	127,855
Common stock dividends	(42,272)				(42,272)
Stock compensation expense	3,042			3,042
Acquisition	334		15	319
Directors stock purchase plan	30		1	29
Employee stock purchase plan	1,069		37	1,032
Restricted stock, net	(703)		54	(757)
Repurchase of common stock	(24,284)		(668)	(23,616)
Balance at end of period at Dec. 31, 2019	1,132,974		34,970	586,622	515,714		(4,332)
Net income	96,953				96,953
Other comprehensive loss, net of tax	23,037						23,037
Total other comprehensive income	119,990
Common stock dividends	(53,175)				(53,175)
Stock compensation expense	3,850			3,850
Acquisition	316		27	289
Stock option plan	289,089		12,769	276,320
Conversion of stock options	3,611			3,611
Employee stock purchase plan	1,681		65	1,616
Restricted stock, net	(458)		46	(504)
Repurchase of common stock	(25,702)		(820)	(24,882)
Adoption of ASC 326 - Financial Instruments - Credit Losses		$ (2,221)				$ (2,221)
Balance at end of period at Dec. 31, 2020	$ 1,469,955		$ 47,057	$ 846,922	$ 557,271		$ 18,705
Accounting Standards Update [Extensible List]	Adoption of ASC 326 - Financial Instruments - Credit Losses

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Stockholders' Equity [Abstract]
Common stock dividends (in dollars per share)	$ 1.20	$ 1.18	$ 1.10
Stock repurchased and retired (in shares)	12,768,949		11,446,197
Stock option plan (in shares)	26,063	15,080	20,888
Director stock purchase plan (in shares)		867
Employee stock purchase plan (in shares)	65,337	37,091	28,996
Restricted stock (in shares)	46,386	54,789	38,360
Repurchase of common stock (in shares)	(820,328)	(668,191)
Accounting Standards Update [Extensible List]	Adoption of ASC 326 - Financial Instruments - Credit Losses

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities:
Net income	$ 96,953	$ 116,433	$ 100,864
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	19,873	13,398	12,516
Provision for credit losses	85,669	4,684	9,023
Share based compensation expense	3,850	3,042	2,645
Deferred income tax / (benefit)	(29,568)	1,719	5,655
Origination of loans held for sale	(1,576,865)	(887,216)	(416,337)
Proceeds from sales of loans held for sale	1,585,690	869,294	441,023
Gains on sales of loans held for sale	(33,418)	(13,006)	(11,699)
Losses on sale of other real estate owned	32	173	200
Investment securities gains	(467)	(77)	(190)
Loss on sales of premises and equipment	0	269	0
Tax benefit/ (expense) associated with share based compensation	(133)	92	299
Net (increase)/ decrease in accrued interest receivable	(15,499)	1,327	(2,622)
Net (increase)/ decrease other assets	1,500	(3,664)	5,020
Net increase/ (decrease) accrued expenses and other liabilities	1,704	(5,804)	(2,721)
Other, net	2,660	(721)	3,970
Net cash provided by operating activities	141,981	99,943	147,646
Investing activities:
Sales/ (purchases) of equity securities	(3,553)		(8,784)
Sales/ (purchases) of equity securities		21,586
Purchases of investments available-for-sale	(633,741)	(326,604)	(161,349)
Proceeds from sales of investment available-for-sale	121,357	2,926	117,354
Proceeds from maturities, calls and principal payments of investments available-for-sale	441,672	199,652	106,114
Net increase in loans	(1,174,467)	(134,012)	(641,521)
Proceeds from the sales of other real estate owned	60	324	1,151
Proceeds from sale of loans held for investment	0	0	59,945
Cash paid for the acquisition of business activity of RPJ, net of cash acquired	(26,925)	0	0
Expenditures for premises and equipment	(5,041)	(5,148)	(10,401)
Net cash used in investing activities	(1,200,196)	(241,276)	(505,004)
Financing activities:
Net increase in deposits	1,270,328	525,439	340,376
Net increase/ (decrease) in in retail repurchase agreements and federal funds purchased	329,552	(113,824)	201,184
Proceeds from advances from borrowings	400,000	2,298,000	5,477,000
Repayment of advances from borrowings	(703,117)	(2,457,834)	(5,633,579)
Retirement of subordinated debt	(10,310)	0	0
Proceeds from issuance of common stock	1,997	1,433	1,395
Stock tendered for payment of withholding taxes	(458)	(703)	(760)
Repurchase of Common Stock	(25,702)	(24,284)	0
Dividends paid	(53,175)	(42,272)	(39,277)
Net cash provided by financing activities	1,209,115	185,955	346,339
Net increase/ (decrease) in cash and cash equivalents	150,900	44,622	(11,019)
Cash and cash equivalents at beginning of year	146,103	101,481	112,500
Cash and cash equivalents at end of year	297,003	146,103	101,481
Supplemental Disclosures:
Interest payments	62,637	84,448	60,504
Income tax payments, net of refunds of $3,755 in 2020	56,430	33,795	25,664
Transfers from loans to residential mortgage loans held for sale	0	0	60,043
Transfers from loans to other real estate owned	70	414	289
WashingtonFirst Bankshares Inc
Investing activities:
Cash acquired in the acquisition of business activity, net of cash paid	0	0	32,487
Revere Bank
Investing activities:
Cash acquired in the acquisition of business activity, net of cash paid	$ 80,442	$ 0	$ 0

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CASH FLOWS - Parenthetical $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Statement of Cash Flows [Abstract]
Income tax refunds	$ 3,755

SIGNIFICANT ACCOUNTING POLICIES

SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
SIGNIFICANT ACCOUNTING POLICIES	SIGNIFICANT ACCOUNTING POLICIES Nature of Operations Sandy Spring Bancorp, Inc. ("Sandy Spring" or, together with its subsidiaries, the "Company"), a Maryland corporation, is the bank holding company for Sandy Spring Bank (the “Bank”), which conducts a full-service commercial banking, mortgage banking and trust business. Services to individuals and businesses include accepting deposits, extending credit to buy real estate or equipment, consumer and commercial loans and lines of credit, general insurance, personal trust, and investment and wealth management services. The Company operates in central Maryland, Northern Virginia, and the greater Washington D.C. market. The Company offers investment and wealth management services through the Bank’s subsidiaries, West Financial Services ("West Financial") and Rembert Pendleton Jackson ("RPJ"). Insurance products are available to clients through Sandy Spring Insurance Corporation ("Sandy Spring Insurance"), and Neff & Associates, which are agencies of Sandy Spring Insurance. 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 financial information. 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. The Company has evaluated subsequent events through the date of the issuance of its financial statements. Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiary, Sandy Spring Bank and its subsidiaries, Sandy Spring Insurance, West Financial and RPJ. Consolidation has resulted in the elimination of all significant intercompany accounts and transactions. See Note 25 for more information on the Company's segments and consolidation. 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, in addition to affecting 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 credit losses and the related allowance, potential impairment of goodwill or other intangible assets, valuation of investment securities and the determination of whether available-for-sale debt securities with fair values less than amortized costs are impaired and require an allowance for credit losses, valuation of other real estate owned ("OREO"), 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. Assets Under Management Assets held for others under fiduciary and agency relationships are not assets of the Company or its subsidiaries and are not included in the accompanying Consolidated Statements of Condition. Trust department income and investment management fees are presented on an accrual basis. 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 an original maturity of three months or less). 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 Consolidated Statements of Income. Most of the Company’s revenue is not within the scope of Accounting Standard Codification (“ASC”) 606 – Revenue from Contracts with Customers. For revenue within the scope of ASC 606, 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 revenue recognition guidance. Wealth Management Income West Financial and RPJ provide 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 Sandy Spring Insurance is a producer. Sandy Spring Insurance 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. An 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 is recognized at month end. The overdraft services obligation is satisfied at the time of the overdraft and revenue is recognized as earned. Residential Mortgage Loans Held for Sale The Company engages in sales of residential mortgage loans originated by the Bank. Loans held for sale are carried at fair value. Fair value is derived from secondary market quotations for similar instruments. The Company measures residential mortgage loans at fair value when the Company first recognizes the loan (i.e., the fair value option), as permitted by current accounting standards. Changes in fair value of these loans are recorded in earnings as a component of mortgage banking activities in non-interest income in the Consolidated Statements of Income. The Company's current practice is to sell the majority of such loans on a servicing released basis. Any retained servicing assets are amortized in proportion to their net servicing fee income over the life of the respective loans. Servicing assets are evaluated for impairment on a periodic basis. Investments Available-for-Sale Debt securities not classified as held to maturity or trading are classified as securities available-for-sale. Securities available-for-sale are acquired as part of the Company's asset/liability management strategy and may be sold in response to changes in interest rates, loan demand, changes in prepayment risk or other factors. Securities available-for-sale are carried at fair value, with unrealized gains or losses based on the difference between amortized cost and fair value, reported net of deferred tax, as accumulated other comprehensive income/ (loss), a separate component of stockholders' equity. The carrying values of securities available-for-sale are adjusted for premium amortization and discount accretion. Premium is amortized to the earliest call date and discount accreted to the maturity date using the effective interest method. Realized gains and losses on security sales or maturities, using the specific identification method, are included as a separate component of non-interest income. Related interest and dividends are included in interest income. Declines in the fair value of individual available-for-sale securities below their amortized cost due to credit-related factors are recognized as an allowance for credit losses. Credit-related factors affecting the determination of whether impairment has occurred include a downgrading of the security below investment grade by a rating agency or due to potential default, a significant deterioration in the financial condition of the issuer, increase in entity-specific credit spreads. Additionally, on any available-for-sale securities with unrealized losses, the Company evaluates its intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in fair value. Equity Securities Equity securities include Federal Reserve Bank stock, Federal Home Loan Bank of Atlanta ("FHLB") stock and other equities that are considered restricted as to marketability and recorded at cost. As these securities do not have readily available market values, they are carried at cost and adjusted for any necessary impairments each reporting period. Loan Financing Receivables The Company’s financing receivables consist primarily of loans that are stated at their principal balance outstanding, net of any unearned income, acquisition fair value marks and deferred loan origination fees and costs. Interest income on loans is accrued at the contractual rate based on the principal balance outstanding. Loan origination fees, net of certain direct origination costs, are deferred and recognized as an adjustment of the related loan yield using the interest method. The Company has provided short-term deferrals of loan principal and/or interest payments up to 180 days for customers who are affected by the COVID-19 pandemic. Customers receiving payment deferrals must meet certain criteria, such as being in good standing and not more than 30 days past due prior to the pandemic. In most cases, the deferred principal and/or interest amounts will be collected at the end of the life of the loan and will not accrue additional interest. The granting of a deferral of principal and/or interest under the Coronavirus Aid, Relief, and Economic Security (“CARES”) Act, which was enacted on March 27, 2020, and based on interagency guidelines, does not subject the loan to the past due, non-accrual, or troubled debt restructurings (“TDR”) policies described below. Upon exiting the loan modification deferral program, the measurement of loan delinquency will resume where it was determined upon entry into the program. The following discussions of past due, non-accrual and TDR policies remain valid for situations not covered by the CARES Act. Loans are considered past due or delinquent when the principal or interest due in accordance with the contractual terms of the loan agreement or any portion thereof remains unpaid after the due date of the scheduled payment. Immaterial shortfalls in payment amounts do not necessarily result in a loan being considered delinquent or past due. If any payments are past due and subsequent payments are resumed without payment of the delinquent amount, the loan shall continue to be considered past due. Whenever any loan is reported delinquent on a principal or interest payment or portion thereof, the amount reported as delinquent is the outstanding principal balance of the loan. Loans, except for consumer installment loans, are placed into non-accrual status when any portion of the loan principal or interest becomes 90 days past due. Management may determine that certain circumstances warrant earlier discontinuance of interest accruals on specific loans if an evaluation of other relevant factors (such as bankruptcy, interruption of cash flows, etc.) indicates collection of amounts contractually due is unlikely. These loans are considered, collectively, to be non-performing loans. Consumer installment loans that are not secured by real estate are not placed on non-accrual, but are charged down to their net realizable value when they are four months past due. Loans designated as non-accrual have all previously accrued but unpaid interest reversed from interest income. Interest income is not recognized on non-accrual loans. All payments received on non-accrual loans are applied using a cost-recovery method to reduce the outstanding principal balance until the loan returns to accrual status. Loans may be returned to accrual status when all principal and interest amounts contractually due are brought current and future payments are reasonably assured. Loans considered to be TDRs are loans that have their terms restructured (e.g., interest rates, loan maturity date, payment and amortization period, etc.) in circumstances that provide payment relief to a borrower experiencing financial difficulty. All restructured collateral-dependent loans are individually assessed for allowance for credit losses and may either be in accruing or non-accruing status. Non-accruing restructured loans may return to accruing status provided doubt has been removed concerning the collectability of principal and interest as evidenced by a sufficient period of payment performance in accordance with the restructured terms. Loans may be removed from the restructured category if the borrower is no longer experiencing financial difficulty, a re-underwriting event took place, and the revised loan terms of the subsequent restructuring agreement are considered to be consistent with terms that can be obtained in the market for loans with comparable credit risk. Allowance for Loan Losses (in accordance with ASC 450 and ASC 310) The allowance for loan losses (“allowance” or “ALL”) is an accounting standard applicable for periods ending December 31, 2019 and earlier and was replaced by the allowance for credit losses standard discussed below. The allowance under this standard represents an amount which, in management's judgment, is appropriate to absorb the probable estimate of losses that may be sustained on outstanding loans at the balance sheet date based on the evaluation of the size and current risk characteristics of the loan portfolio. The allowance is reduced by charge-offs, net of recoveries of previous losses, and is increased or decreased by a provision or credit for loan losses, which is recorded as a current period operating expense. The allowance is based on the basic principle that a loss be accrued when it is probable that the loss has occurred and the amount of the loss can be reasonably estimated. The Company’s methodology for estimating the allowance includes a general component reflecting historical losses, as adjusted, by loan portfolio segment, and a specific component for impaired loans. The general component is based upon historical loss experience by each portfolio segment measured, over the prior eight quarters weighted equally. The historical loss experience is supplemented to address various risk characteristics of the Company’s loan portfolio including: • trends in delinquencies and other non-performing loans; • changes in the risk profile related to large loans in the portfolio; • changes in the categories of loans comprising the loan portfolio; • concentrations of loans to specific industry segments; • changes in economic conditions on both a local and national level; • changes in the Company’s credit administration and loan portfolio management processes; and • the quality of the Company’s credit risk identification processes. The general component is calculated in two parts based on an internal risk classification of loans within each portfolio segment. Reserves on loans considered to be “classified” under regulatory guidance are calculated separately from loans considered to be “pass” rated under the same guidance. This segregation allows the Company to monitor the allowance component applicable to higher risk loans separate from the remainder of the portfolio in order to better manage risk and reasonably determine the sufficiency of reserves. Integral to the assessment of the allowance process is an evaluation that is performed to determine whether a specific allowance on an impaired credit is warranted. For the particular loan that may have potential impairment, an appraisal will be ordered depending on the time elapsed since the prior appraisal, the loan balance and/or the result of the internal evaluation. The Company typically relies on current (12 months old or less) third party appraisals of the collateral to assist in measuring impairment. In the cases in which the Company does not rely on a third party appraisal, an internal evaluation is prepared by an approved credit officer. A current appraisal on large loans is usually obtained if the appraisal on file is more than 12 months old and there has been a material change in market conditions, zoning, physical use or the appropriateness of the collateral based on an internal evaluation. The Company’s policy is to strictly adhere to regulatory appraisal standards. If an appraisal is ordered, no more than a 30 day turnaround is requested from the appraiser, who is selected by Credit Administration from an approved appraiser list. After receipt of the updated appraisal, the assigned credit officer will recommend to the Chief Credit Officer whether a specific allowance or a charge-off should be taken. When losses are confirmed, a charge-off is taken that is at least in the amount of the collateral deficiency as determined by the independent third party appraisal. Any further collateral deterioration results in either further specific reserves being established or additional charge-offs. The Chief Credit Officer has the authority to approve a specific allowance or charge-off between monthly credit committee meetings to ensure that there are no significant time lapses during this process. The portion of the allowance representing specific allowances is established on individually impaired loans. As a practical expedient, for collateral dependent loans, the Company measures impairment based on the net realizable value of the underlying collateral. For loans on which the Company has not elected to use a practical expedient to measure impairment, the Company will measure impairment based on the present value of expected future cash flows discounted at the loan’s effective interest rate. In determining the cash flows to be included in the discount calculation the Company considers the following factors that combine to estimate the probability and severity of potential losses: • the borrower’s overall financial condition; • resources and payment record; • demonstrated or documented support available from financial guarantors; and • the appropriateness of collateral value and the ultimate realization of that value at liquidation. Allowance for Credit Losses (in accordance with ASC 326) The allowance for credit losses (“allowance” or “ACL”) represents an amount which, in management's judgment, represents the lifetime expected credit losses that may be sustained on outstanding loans at the statement of condition date based on the evaluation of the size and current risk characteristics of the loan portfolio, past events, current conditions, reasonable and supportable forecasts of future economic conditions and prepayment experience. The allowance is measured and recorded upon the initial recognition of a financial asset. The allowance is reduced by charge-offs, net of recoveries of previous losses, and is increased or decreased by a provision for credit losses, which is recorded as a current period expense. Determination of the appropriateness of the allowance is inherently complex and requires the use of significant and highly subjective estimates. The reasonableness of the allowance is reviewed periodically by the Risk Committee of the board of directors and formally approved quarterly by that same committee of the board. The Company’s methodology for estimating the allowance includes: (1) a collective quantified reserve that reflects the Company’s historical default and loss experience adjusted for expected economic conditions throughout a reasonable and supportable period and the Company’s prepayment and curtailment rates; (2) collective qualitative factors that consider concentrations of the loan portfolio, expected changes to the economic forecasts, large relationships, early delinquencies, and factors related to credit administrations, including, among others, loan-to-value ratios, borrowers’ risk rating and credit score migrations; and (3) individual allowances on collateral-dependent loans where borrowers are experiencing financial difficulty or when the Company determines that foreclosure is probable. The Company excludes accrued interest from the measurement of the allowance as the Company has a non-accrual policy to reverse any accrued, uncollected interest income as loans are moved to non-accrual status. Loans are pooled into segments based on the similar risk characteristics of the underlying borrowers, in addition to consideration of collateral type, industry and business purpose of the loans. Portfolio segments used to estimate the allowance are the same as portfolio segments used for general credit risk management purposes. Refer to Note 5 for more details on the Company’s portfolio segments. The Company applies two calculation methodologies to estimate the collective quantified component of the allowance: discounted cash flows method and weighted average remaining life method. Allowance estimates on commercial acquisition, development and construction (“AD&C”) and residential construction segments are based on the weighted average remaining life method. Allowance estimates on all other portfolio segments are based on the discounted cash flows method. Segments utilizing the discounted cash flows method are further sub-segmented into risk level pools, determined either by risk rating for commercial loans or Beacon Scores ranges for residential and consumer loans. To better manage risk and reasonably determine the sufficiency of reserves, this segregation allows the Company to monitor the allowance component applicable to higher risk loans separate from the remainder of the portfolio. Collective calculation methodologies utilize the Company’s historical default and loss experience adjusted for economic forecasts. The reasonable and supportable forecast period represents a two-year economic outlook for the applicable economic variables. Following the end of the reasonable and supportable forecast period expected losses revert back to the historical mean over the next two years on a straight-line basis. Economic variables that have the most significant impact on the allowance include: unemployment rate, house price index and number of business bankruptcies. Contractual loan level cash flows within the discounted cash flows methodology are adjusted for the Company’s historical prepayment and curtailment rate experience. The individual reserve assessment is applied to collateral dependent loans where borrowers are experiencing financial difficulty or when the Company determines that a foreclosure is probable. The determination of the fair value of the collateral depends on whether a repayment of the loan is expected to be from the sale or the operation of the collateral. When a repayment is expected from the operation of the collateral, the Company uses the present value of expected cash flows from the operation of the collateral as the fair value. When the repayment of the loan is expected from the sale of the collateral the fair value of the collateral is based on an observable market price or the collateral’s appraised value, less estimated costs to sell. Third-party appraisals used in the individual reserve assessment are conducted at least annually, or more frequently if deemed necessary, with underlying assumptions that are reviewed by management. Internal evaluations of collateral value are conducted quarterly to ensure any further deterioration of the collateral value is recognized on a timely basis. During the individual reserve assessment, management also considers the potential future changes in the value of the collateral over the remainder of the loan’s remaining life. The Company may receive updated appraisals which contradict the preliminary determination of fair value used to establish an individual allowance on a loan. In these instances the individual allowance is adjusted to reflect the Company’s evaluation of the updated appraised fair value. In the event a loss was previously confirmed and the loan was charged down to the estimated fair value based on a previous appraisal, the balance of partially charged-off loans are not subsequently increased, but could be further decreased depending on the direction of the change in fair value. Payments on fully or partially charged-off loans are accounted for under the cost-recovery method. Under this method, all payments received are applied on a cash basis to reduce the entire outstanding principal balance, then to recognize a recovery of all previously charged-off amounts before any interest income may be recognized. Based on the individual reserve assessment, if the Company determines that the fair value of the collateral is less than the amortized cost basis of the loan, an individual allowance will be established measured as the difference between the fair value of the collateral (less costs to sell) and the amortized cost basis of the loan. Once a loss has been confirmed, the loan is charged down to its estimated fair value. Large groups of smaller non-accrual homogeneous loans, including residential permanent and construction mortgages and consumer installment loans, are not individually evaluated for allowance. These portfolios are reserved for on a collective basis using historical loss rates of similar loans over the weighted average life of each pool. The Company reviews its unfunded commitments to determine if they are unconditionally cancellable by the Company. If the unfunded commitment is determined to not be unconditionally cancellable by the Company, a reserve for unfunded commitments is established. An estimate of the reserve for unfunded commitments considers both the likelihood that the funding will occur and an estimate of expected credit losses over the life of the commitment. Management believes it uses relevant information available to make determinations about the allowance and that it has established the existing allowance in accordance with GAAP. However, the determination of the allowance requires significant judgment, and estimates of expected lifetime losses in the loan portfolio can vary significantly from the amounts actually observed. While management uses available information to recognize expected losses, future additions to the allowance may be necessary based on changes in the loans comprising the portfolio, changes in the current and forecasted economic conditions, changes to the interest rate environment which may directly impact prepayment and curtailment rate assumptions, and changes in the financial condition of borrowers. Loans Acquired with Deteriorated Credit Quality (in accordance with ASC 310-30) Acquired loans with evidence of credit deterioration since their origination, commonly referred to as purchased credit impaired ("PCI") loans, are recorded at their initial fair values as of the date of the acquisition. The accounting standard for PCI loans was applicable for periods ending December 31, 2019 and earlier and was replaced with the accounting standard for purchase credit deteriorated loans as discussed below. 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 (non-accretable 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. Acquired Loans (in accordance with ASC 326) Loans acquired in connection with acquisitions are recorded at their acquisition-date fair value. The allowance for credit losses related to the acquired loan portfolio is not carried over. Acquired loans are classified into two categories based on the credit risk characteristics of the underlying borrowers as either purchased credit deteriorated (“PCD”) loans, or loans with no evidence of credit deterioration (“non-PCD”). PCD loans are defined as a loan or pool of loans that have experienced more-than-insignificant credit deterioration since the origination date. The Company uses a combination of individual and pooled review approaches to determine if acquired loans are PCD. At acquisition, the Company considers a number of factors to determine if an acquired loan or pool of loans has experienced more-than-insignificant credit deterioration. These factors include: • loans classified as non-accrual, • loans with risk rating of special mention or worse (using the Company's risk rating scale), • loans with multiple risk rating downgrades since origination, • loans with evidence of being 60 days or more past due, • loans previously modified in a troubled debt restructuring, • loans that received an interest only or payment deferral modification, and • loans in industries that show evidence of additional risk due to economic conditions. The initial allowance related to PCD loans that share similar risk characteristics is established using a pooled approach. The Company uses either a discounted cash flow or weighted average remaining life method to determine the required level of the allowance. PCD loans that were classified as non-accrual as of the acquisition date and are collateral dependent are assessed for allowance on an individual basis. For PCD loans, an initial allowance is established on the acquisition date and added to the fair value of the loan to arrive at acquisition date amortized cost. Accordingly, no provision for credit losses is recognized on PCD loans at the acquisition date. Subsequent to the acquisition date, the initial allowance on PCD loans will increase or decrease based on future evaluations, with changes recognized in the provision for credit losses. Non-PCD loans are pooled into segments together with originated loans that share similar risk characteristics and have an allowance established on the acquisition date, which is recognized in the current period provision for credit losses. Determining the fair value of the acquired loans involves estimating the principal and interest payment cash flows expected to be collected on the loans and discounting those cash flows at a market rate of interest. Management considers a number of factors in evaluating the acquisition date fair value including the remaining life, interest rate profile, market interest rate environment, payment schedules, risk ratings, probability of default and loss given default, and estimated prepayment rates. For PCD loans, the non-credit discount or premium is allocated to individual loans as determined by the difference between the loan’s unpaid principal balance and amortized cost basis. The non-credit premium or discount is recognized into interest income on a level yield basis over the

ACQUISITION OF REVERE BANK

ACQUISITION OF REVERE BANK	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
ACQUISITION OF REVERE BANK	ACQUISITION OF REVERE BANK On April 1, 2020 (“Acquisition Date”), the Company completed the acquisition of Revere Bank (“Revere”), a Maryland chartered commercial bank, in accordance with the definitive agreement that was entered into on September 23, 2019 by and among the Company, the Bank and Revere. In connection with the completion of the merger, former Revere shareholders received 1.05 shares of Sandy Spring common stock for each share of Revere common stock they held. Based on the $22.64 per share closing price of Sandy Spring common stock on March 31, 2020, and including the fair value of options converted or cashed-out, the total transaction value was approximately $293.0 million. Upon completion of the acquisition, Sandy Spring shareholders owned approximately 74 percent of the combined company, and former Revere shareholders owned approximately 26 percent. As of March 31, 2020, Revere, headquartered in Rockville, MD, had more than $2.8 billion in assets and operated 11 full-service community banking offices throughout the Washington D.C. metropolitan region. The acquisition of Revere was accounted for as a business combination using the acquisition method of accounting and, accordingly, assets acquired, liabilities assumed, and consideration paid are recorded at estimated fair values on the Acquisition Date. The provisional amount of goodwill recognized as of the Acquisition Date was approximately $0.8 million. After immaterial adjustments recorded during the fourth quarter of 2020, the provisional amount of goodwill recognized as of December 31, 2020 was $0.5 million. The Company will continue to keep the measurement of goodwill open for any additional adjustments to the fair value of certain accounts, for example loans, that may arise during the Company's final review procedures of any updated information. If considered necessary, any subsequent adjustments to the fair values of assets acquired and liabilities assumed, identifiable intangible assets, or other purchase accounting adjustments will result in adjustments to goodwill within the first 12 months following the Acquisition Date. The goodwill is not expected to be deductible for tax purposes. As a result of the integration of the operations of Revere, it is not practicable to determine revenue or net income included in the Company’s consolidated operating results relating to Revere since the date of acquisition, as Revere’s results cannot be separately identified. Comparative pro-forma financial statements for the prior year period were not presented, as adjustments to those statements would not be indicative of what would have occurred had the acquisition taken place on January 1, 2019. In particular, adjustments that would have been necessary to be made to record the loans at fair value, the provision of credit losses or the core deposit intangible would not be practicable to estimate. The consideration paid for Revere’s common equity and outstanding stock options and the provisional fair values of acquired identifiable assets and assumed identifiable liabilities as of December 31, 2020 were as follows: (Dollars in thousands, except per share data) December 31, 2020 Purchase price: Fair value of common shares issued (12,768,949 shares) based on Sandy Spring's share price of $22.64 $ 289,089 Fair value of Revere stock options converted to Sandy Spring stock options 3,611 Cash paid for cashed-out Revere stock options 291 Cash for fractional shares 11 Total purchase price $ 293,002 Identifiable assets: Cash and cash equivalents $ 80,744 Investments available-for-sale 180,752 Loans 2,502,244 Premises and equipment 3,443 Accrued interest receivable 7,651 Core deposit intangible asset 18,360 Other assets 53,162 Total identifiable assets $ 2,846,356 Identifiable liabilities: Deposits $ 2,322,422 Borrowings 205,514 Other liabilities 25,933 Total identifiable liabilities $ 2,553,869 Provisional fair value of net assets acquired including identifiable intangible assets 292,487 Provisional resulting goodwill $ 515

CASH AND DUE FROM BANKS

CASH AND DUE FROM BANKS	12 Months Ended
	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
CASH AND DUE FROM BANKS	CASH AND DUE FROM BANKSThe Federal Reserve Act requires that banks maintain cash reserve balances with the Federal Reserve Bank based principally on the type and amount of their deposits. At its option, the Company maintains additional balances to compensate for clearing and safekeeping services. The average balance maintained in 2020 was $236.3 million and in 2019 was $105.3 million.

INVESTMENTS

INVESTMENTS	12 Months Ended
	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
INVESTMENTS	INVESTMENTS Investments available-for-sale The amortized cost and estimated fair values of investments available-for-sale at December 31 are presented in the following table: 2020 2019 Amortized Cost Gross Unrealized Gross Unrealized Estimated Fair Amortized Cost Gross Unrealized Gross Unrealized Estimated Fair U.S. treasuries and government agencies $ 42,750 $ 549 $ (2) $ 43,297 $ 260,294 $ 887 $ (2,686) $ 258,495 State and municipal 377,108 13,470 (211) 390,367 229,309 4,377 (37) 233,649 Mortgage-backed and asset-backed 881,201 24,078 (847) 904,432 568,373 3,268 (882) 570,759 Corporate debt 9,100 825 — 9,925 9,100 452 — 9,552 Trust preferred — — — — 310 — — 310 Total debt securities 1,310,159 38,922 (1,060) 1,348,021 1,067,386 8,984 (3,605) 1,072,765 Marketable equity securities — — — — 568 — — 568 Total investments available-for-sale $ 1,310,159 $ 38,922 $ (1,060) $ 1,348,021 $ 1,067,954 $ 8,984 $ (3,605) $ 1,073,333 Any unrealized losses in the U.S. treasuries and government agencies, state and municipal, mortgage-backed and asset-backed investment securities at December 31, 2020 are due to changes in interest rates and not credit-related events. As such, no allowance for credit losses is required at December 31, 2020. Unrealized losses on investment securities are expected to recover over time as these securities approach maturity. The Company does not intend to sell, nor is it more likely than not that it will be required to sell, these securities and has sufficient liquidity to hold these securities for an adequate period of time, which may be maturity, to allow for any anticipated recovery in fair value. The mortgage-backed and asset-backed portfolio at December 31, 2020 is composed entirely of either the most senior tranches of GNMA, FNMA or FHLMC collateralized mortgage obligations ($318.6 million), GNMA, FNMA or FHLMC mortgage-backed securities ($520.1 million) and SBA asset-backed securities ($65.7 million). Gross unrealized losses and fair values by length of time that individual available-for-sale securities have been in an unrealized loss position at December 31 are presented in the following tables: December 31, 2020 Number Less Than 12 Months 12 Months or More Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses U.S. treasuries and government agencies 2 $ 25,369 $ 2 $ — $ — $ 25,369 $ 2 State and municipal 8 22,753 211 — — 22,753 211 Mortgage-backed and asset-backed 24 44,746 154 76,879 693 121,625 847 Total 34 $ 92,868 $ 367 $ 76,879 $ 693 $ 169,747 $ 1,060 December 31, 2019 Number Less Than 12 Months 12 Months or More Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses U.S. treasuries and government agencies 12 $ 133,221 $ 2,211 $ 17,911 $ 475 $ 151,132 $ 2,686 State and municipal 3 7,227 37 — — 7,227 37 Mortgage-backed and asset-backed 35 107,917 508 76,867 374 184,784 882 Total 50 $ 248,365 $ 2,756 $ 94,778 $ 849 $ 343,143 $ 3,605 The Company has allocated mortgage-backed and asset-backed securities into the four maturity groupings reflected in the following table using the expected average life of the individual securities based on statistics provided by independent third-party industry sources. Expected maturities will differ from contractual maturities as borrowers may have the right to prepay obligations with or without prepayment penalties. The estimated fair values and amortized costs of debt securities available-for-sale by contractual maturity at December 31 are provided in the following table: December 31, 2020 December 31, 2019 (In thousands) Fair Value Amortized Cost Fair Value Amortized Cost U.S. treasuries and government agencies: One year or less $ 33,963 $ 33,833 $ 69,799 $ 69,330 One to five years 9,334 8,917 96,709 96,507 Five to ten years — — — — After ten years — — 91,987 94,457 State and municipal: One year or less 16,581 16,458 33,311 33,054 One to five years 44,910 43,857 76,723 75,432 Five to ten years 59,059 56,130 75,820 73,741 After ten years 269,817 260,663 47,795 47,082 Mortgage-backed and asset-backed: One year or less 1 1 852 822 One to five years 21,637 21,229 7,125 6,969 Five to ten years 74,142 72,481 55,226 54,799 After ten years 808,652 787,490 507,556 505,783 Corporate debt: One year or less — — — — One to five years 2,318 2,100 — — Five to ten years 7,607 7,000 9,552 9,100 After ten years — — — — Trust preferred: One year or less — — — — One to five years — — — — Five to ten years — — — — After ten years — — 310 310 Total available-for-sale debt securities $ 1,348,021 $ 1,310,159 $ 1,072,765 $ 1,067,386 At December 31, 2020 and 2019, investments available-for-sale with a book value of $465.7 million and $424.8 million, respectively, were pledged as collateral for certain government deposits and for other purposes as required or permitted by law. The outstanding balance of no single issuer, except for U.S. government agency securities, exceeded ten percent of stockholders' equity at December 31, 2020 and 2019. Equity securities Other equity securities at the dates indicated are presented in the following table: (In thousands) 2020 2019 Federal Reserve Bank stock $ 38,650 $ 22,559 Federal Home Loan Bank of Atlanta stock 26,433 29,244 Other equity securities 677 — Total equity securities $ 65,760 $ 51,803 Investment securities gains Gross realized gains and losses on all investments for the years ended December 31 are presented in the following table: (In thousands) 2020 2019 2018 Gross realized gains from sales of investments available-for-sale $ 1,297 $ 14 $ 2,519 Gross realized losses from sales of investments available-for-sale (1,068) (2) (2,343) Net gains from calls of investments available-for-sale 238 65 14 Net investment securities gains $ 467 $ 77 $ 190

LOANS

LOANS	12 Months Ended
	Dec. 31, 2020
Receivables [Abstract]
LOANS	LOANS The lending business of the Company is based on understanding, measuring and controlling the credit risk inherent in the loan portfolio. The Company’s loan portfolio is subject to varying degrees of credit risk. Credit risk entails both general risks, which are inherent in the process of lending, and risk specific to individual borrowers. The Company’s credit risk is mitigated through portfolio diversification, which limits exposure to any single customer, industry or collateral type. Outstanding loan balances at December 31, 2020 and 2019 are net of unearned income, including net deferred loan fees of $24.5 million and $1.8 million, respectively. Net deferred loan fees at December 31, 2020, included $21.2 million in net fees related to the loans originated under the Paycheck Protection Program (“PPP”). The loan portfolio segment balances at December 31 are presented in the following table: (In thousands) 2020 2019 Commercial real estate: Commercial investor real estate $ 3,634,720 $ 2,169,156 Commercial owner-occupied real estate 1,642,216 1,288,677 Commercial AD&C 1,050,973 684,010 Commercial business 2,267,548 801,019 Total commercial loans 8,595,457 4,942,862 Residential real estate: Residential mortgage 1,105,179 1,149,327 Residential construction 182,619 146,279 Consumer 517,254 466,764 Total residential and consumer loans 1,805,052 1,762,370 Total loans $ 10,400,509 $ 6,705,232 The fair value of the financial assets acquired in the Revere acquisition included loans receivable with a gross amortized cost basis of $2.5 billion. Of the loans acquired, the Company identified $974.8 million of loans that were classified as PCD. An initial allowance for credit losses of $18.6 million was recorded through a gross-up adjustment to fair values of PCD loans. A fair value premium related to other factors totaled $4.5 million and will amortize to interest income over the remaining life of each loan. Total fair value of PCD loans as of the Acquisition Date was $960.7 million. Of the PCD loans, $11.3 million were non-accruing at the time of acquisition. As of December 31, 2020, the Revere PCD loans had a fair value of $911.4 million, with a remaining unamortized fair value premium of $4.0 million. Refer to Note 1 for more details on factors considered in the PCD assessment. At the Acquisition Date, non-PCD loans totaled $1.5 billion and had a net fair value premium of $2.1 million, which will amortize to interest income over the remaining life of each loan. As of December 31, 2020, the Revere non-PCD loans had a fair value of $1.3 billion with a remaining unamortized fair value premium of $1.4 million. See Note 1 for more information on the Company’s accounting policy for acquired loans and Note 2 for more information on the Revere acquisition. Portfolio Segments The Company currently manages its credit products and the respective exposure to credit losses (credit risk) by the following specific portfolio segments which are levels at which the Company develops and documents its systematic methodology to determine the allowance for credit losses attributable to each respective portfolio segment. These segments are: • Commercial investor real estate loans - Commercial investor real estate loans consist of loans secured by nonowner-occupied properties where an established banking relationship exists and involves investment properties for warehouse, retail, and office space with a history of occupancy and cash flow. This commercial investor real estate category contains mortgage loans to the developers and owners of commercial real estate where the borrower intends to operate or sell the property at a profit and use the income stream or proceeds from the sale(s) to repay the loan. • Commercial owner-occupied real estate loans - Commercial owner-occupied real estate loans consist of commercial mortgage loans secured by owner-occupied properties where an established banking relationship exists and involves a variety of property types to conduct the borrower’s operations. The decision to extend a loan is based upon the borrower’s financial health and the ability of the borrower and the business to repay. The primary source of repayment for this type of loan is the cash flow from the operations of the business. • Commercial acquisition, development and construction loans - Commercial acquisition, development and construction loans are intended to finance the construction of commercial properties and include loans for the acquisition and development of land. Construction loans represent a higher degree of risk than permanent real estate loans and may be affected by a variety of additional factors such as the borrower’s ability to control costs and adhere to time schedules and the risk that constructed units may not be absorbed by the market within the anticipated time frame or at the anticipated price. The loan commitment on these loans often includes an interest reserve that allows the lender to periodically advance loan funds to pay interest charges on the outstanding balance of the loan. • Commercial business loans - Commercial loans are made to provide funds for equipment and general corporate needs. Repayment of a loan primarily comes from the funds obtained from the operation of the borrower’s business. Commercial loans also include lines of credit that are utilized to finance a borrower’s short-term credit needs and/or to finance a percentage of eligible receivables and inventory. Loans issued under the PPP are also included in this category, a substantial portion of which are expected to be forgiven by the Small Business Administration pursuant to the CARES Act. • Residential mortgage loans - The residential mortgage loans category contains permanent mortgage loans principally to consumers secured by residential real estate. Residential real estate loans are evaluated for the adequacy of repayment sources at the time of approval, based upon measures including credit scores, debt-to-income ratios, and collateral values. Loans may be either conforming or non-conforming. • Residential construction loans - The Company makes residential construction loans generally to provide interim financing on residential property during the construction period. Borrowers are typically individuals who will ultimately occupy the single-family dwelling. Loan funds are disbursed periodically as pre-specified stages of completion are attained based upon site inspections . • Consumer loans - This category of loans includes primarily home equity loans and lines, installment loans, personal lines of credit, and other loans. The home equity category consists mainly of revolving lines of credit to consumers which are secured by residential real estate. These loans are typically secured with second mortgages on the homes. Other consumer loans include installment loans used by customers to purchase automobiles, boats and recreational vehicles. Loans to Related Parties Certain directors and executive officers have loan transactions with the Company. The following schedule summarizes changes in amounts of loans outstanding, both direct and indirect, to these persons during the periods indicated: (In thousands) 2020 2019 2018 Balance at January 1 $ 51,367 $ 54,208 $ 36,712 Additions 46,846 4,737 21,871 Repayments (2,208) (7,578) (4,375) Balance at December 31 $ 96,005 $ 51,367 $ 54,208

CREDIT QUALITY ASSESSMENT

CREDIT QUALITY ASSESSMENT	12 Months Ended
	Dec. 31, 2020
Credit Loss [Abstract]
CREDIT QUALITY ASSESSMENT	CREDIT QUALITY ASSESSMENT Allowance for Credit Losses The Company completed the implementation of the CECL standard during the first quarter of 2020. The new guidance requires additional disclosures and introduces certain changes to definitions previously used under allowance for credit losses guidance. Accordingly, the following sections present separate disclosures compliant with the new and the legacy disclosure requirements. See Note 1 for more details on the accounting policy for credit losses and on the implementation of the new accounting standard. Summary information on the allowance for credit loss activity for the years ended December 31 is provided in the following table: (In thousands) 2020 2019 2018 Balance at beginning of year $ 56,132 $ 53,486 $ 45,257 Initial allowance on PCD loans at adoption of ASC 326 2,762 — — Transition impact of adopting ASC 326 2,983 — — Initial allowance on Revere PCD loans 18,628 — — Provision for credit losses 85,669 4,684 9,023 Loan charge-offs (1,819) (2,668) (1,416) Loan recoveries 1,012 630 622 Net charge-offs (807) (2,038) (794) Balance at period end $ 165,367 $ 56,132 $ 53,486 The following table provides summary information regarding collateral dependent loans individually evaluated for credit loss at the dates indicated: (In thousands) 2020 2019 Collateral dependent loans individually evaluated for credit loss with an allowance $ 20,717 $ 15,333 Collateral dependent loans individually evaluated for credit loss without an allowance 77,001 9,440 Total individually evaluated collateral dependent loans $ 97,718 $ 24,773 Allowance for credit losses related to loans evaluated individually $ 11,405 $ 5,501 Allowance for credit losses related to loans evaluated collectively 153,962 50,631 Total allowance for credit losses $ 165,367 $ 56,132 The below section presents allowance for credit losses disclosures in line with the new CECL disclosure requirements. The following tables provide information on the activity in the allowance for credit losses by the respective loan portfolio segment for the years ended December 31: 2020 Commercial Real Estate Residential Real Estate Commercial Commercial Commercial Commercial Residential Residential Consumer Total Balance as of December 31, 2019 $ 18,407 $ 6,884 $ 7,590 $ 11,395 $ 8,803 $ 967 $ 2,086 $ 56,132 Initial allowance on PCD loans at adoption of ASC 326 1,114 — — 1,549 — — 99 2,762 Transition impact of adopting ASC 326 (3,125) 387 2,576 2,988 (388) (275) 820 2,983 Initial allowance on Revere PCD loans 7,973 2,782 1,248 6,289 243 6 87 18,628 Provision 33,431 10,008 10,743 24,374 3,016 798 3,299 85,669 Charge-offs (411) — — (491) (484) — (433) (1,819) Recoveries 15 — — 702 105 6 184 1,012 Net (charge-offs)/ recoveries (396) — — 211 (379) 6 (249) (807) Balance at end of period $ 57,404 $ 20,061 $ 22,157 $ 46,806 $ 11,295 $ 1,502 $ 6,142 $ 165,367 Total loans $ 3,634,720 $ 1,642,216 $ 1,050,973 $ 2,267,548 $ 1,105,179 $ 182,619 $ 517,254 $ 10,400,509 Allowance for credit losses to total loans ratio 1.58 % 1.22 % 2.11 % 2.06 % 1.02 % 0.82 % 1.19 % 1.59 % Balance of loans individually evaluated for credit loss $ 45,227 $ 11,561 $ 15,044 $ 23,648 $ 1,874 $ — $ 364 $ 97,718 Allowance related to loans evaluated individually $ 1,273 $ — $ 603 $ 9,529 $ — $ — $ — $ 11,405 Individual allowance to loans evaluated individually ratio 2.81 % — % 4.01 % 40.30 % — % — % — % 11.67 % Balance of loans collectively evaluated for credit loss $ 3,589,493 $ 1,630,655 $ 1,035,929 $ 2,243,900 $ 1,103,305 $ 182,619 $ 516,890 $ 10,302,791 Allowance related to loans evaluated collectively $ 56,131 $ 20,061 $ 21,554 $ 37,277 $ 11,295 $ 1,502 $ 6,142 $ 153,962 Collective allowance to loans evaluated collectively ratio 1.56 % 1.23 % 2.08 % 1.66 % 1.02 % 0.82 % 1.19 % 1.49 % The following table presents collateral dependent loans individually evaluated for credit losses with the associated allowances for credit losses by the applicable portfolio segment: 2020 Commercial Real Estate Residential Real Estate Total (In thousands) Commercial Commercial Commercial Commercial Residential Mortgage Residential Construction Consumer Loans individually evaluated for credit losses with an allowance: Non-accruing $ 4,913 $ — $ 1,328 $ 11,178 $ — $ — $ — $ 17,419 Restructured accruing — — — 589 — — — 589 Restructured non-accruing 699 — — 2,010 — — — 2,709 Balance $ 5,612 $ — $ 1,328 $ 13,777 $ — $ — $ — $ 20,717 Allowance $ 1,273 $ — $ 603 $ 9,529 $ — $ — $ — $ 11,405 Loans individually evaluated for credit losses without an allowance: Non-accruing $ 39,615 $ 9,315 $ 13,716 $ 9,118 $ — $ — $ — $ 71,764 Restructured accruing — — — 126 1,602 — — 1,728 Restructured non-accruing — 2,246 — 627 272 — 364 3,509 Balance $ 39,615 $ 11,561 $ 13,716 $ 9,871 $ 1,874 $ — $ 364 $ 77,001 Total individually evaluated loans: Non-accruing $ 44,528 $ 9,315 $ 15,044 $ 20,296 $ — $ — $ — $ 89,183 Restructured accruing — — — 715 1,602 — — 2,317 Restructured non-accruing 699 2,246 — 2,637 272 — 364 6,218 Balance $ 45,227 $ 11,561 $ 15,044 $ 23,648 $ 1,874 $ — $ 364 $ 97,718 Unpaid contractual principal balance $ 49,920 $ 15,309 $ 16,040 $ 30,958 $ 3,225 $ — $ 364 $ 115,816 The following table presents average principal balance of total non-accrual loans, contractual interest due and interest income recognized on a cash basis on non-accrual loans for the periods indicated below: 2020 Commercial Real Estate Residential Real Estate Total (In thousands) Commercial Commercial Commercial Commercial Residential Mortgage Residential Construction Consumer Average non-accrual loans for the period $ 26,849 $ 6,605 $ 4,267 $ 16,532 $ 11,634 $ — $ 6,675 $ 72,562 Contractual interest income due on non-accrual loans during the period $ 6,547 $ 2,741 $ 4,505 $ 2,858 $ 918 $ — $ 732 $ 18,301 There was no interest income recognized on non-accrual loans during the year ended December 31, 2020. See Note 1 for additional information on the Company's policies for non-accrual loans. Loans designated as non-accrual have all previously accrued but unpaid interest reversed from interest income. During the year ended December 31, 2020, new loans placed on non-accrual status totaled $85.3 million and the related amount of reversed uncollected accrued interest was $2.2 million. The below section presents historical allowance for credit losses disclosures in line with the legacy disclosure requirements. The following table provides information on the activity in the allowance for credit losses by the respective loan portfolio segment for the period indicated: 2019 Commercial Real Estate Residential Real Estate Commercial Commercial Commercial Commercial Residential Residential Consumer Balance at beginning of year $ 17,603 $ 6,307 $ 5,944 $ 11,377 $ 8,881 $ 1,261 $ 2,113 $ 53,486 Provision/ (credit) 788 577 1,418 1,164 474 (302) 565 4,684 Charge-offs — — — (1,195) (690) — (783) (2,668) Recoveries 16 — 228 49 138 8 191 630 Net (charge-offs)/ recoveries 16 — 228 (1,146) (552) 8 (592) (2,038) Balance at end of period $ 18,407 $ 6,884 $ 7,590 $ 11,395 $ 8,803 $ 967 $ 2,086 $ 56,132 Total loans $ 2,169,156 $ 1,288,677 $ 684,010 $ 801,019 $ 1,149,327 $ 146,279 $ 466,764 $ 6,705,232 Allowance for loans total loans ratio 0.85 % 0.53 % 1.11 % 1.42 % 0.77 % 0.66 % 0.45 % 0.84 % Balance of loans specifically evaluated for impairment $ 9,212 $ 4,148 $ 829 $ 8,867 $ 1,717 $ — $ — $ 24,773 Allowance for loans specifically evaluated for impairment $ 1,529 $ 23 $ 132 $ 3,817 $ — $ — $ — $ 5,501 Specific allowance to specific loans ratio 16.60 % 0.55 % 15.92 % 43.05 % — % — % — % 22.21 % Balance of loans collectively evaluated $ 2,150,400 $ 1,284,529 $ 683,181 $ 789,613 $ 1,147,602 $ 146,279 $ 465,771 $ 6,667,375 Allowance for loans collectively evaluated $ 16,878 $ 6,861 $ 7,458 $ 7,578 $ 8,803 $ 967 $ 2,086 $ 50,631 Collective allowance to collective loans ratio 0.78 % 0.53 % 1.09 % 0.96 % 0.77 % 0.66 % 0.45 % 0.76 % Balance of loans acquired with deteriorated credit quality $ 9,544 $ — $ — $ 2,539 $ 8 $ — $ 993 $ 13,084 Allowance for loans acquired with deteriorated credit quality $ — $ — $ — $ — $ — $ — $ — $ — Allowance for loans acquired with deteriorated credit quality ratio — % — % — % — % — % — % — % — % The following tables present the recorded investment with respect to impaired loans, the associated allowance by the applicable portfolio segment and the unpaid contractual principal balance of the impaired loans: 2019 Commercial Real Estate Total Recorded Investment in Impaired (In thousands) Commercial Commercial Commercial Commercial All Impaired loans with a specific allowance: Non-accruing $ 5,448 $ 767 $ 829 $ 5,608 $ — $ 12,652 Restructured accruing — — — 266 — 266 Restructured non-accruing 437 122 — 1,856 — 2,415 Balance $ 5,885 $ 889 $ 829 $ 7,730 $ — $ 15,333 Allowance $ 1,529 $ 23 $ 132 $ 3,817 $ — $ 5,501 Impaired loans without a specific allowance: Non-accruing $ 2,552 $ 1,522 $ — $ 114 $ — $ 4,188 Restructured accruing 775 — — 151 1,444 2,370 Restructured non-accruing — 1,737 — 872 273 2,882 Balance $ 3,327 $ 3,259 $ — $ 1,137 $ 1,717 $ 9,440 Total impaired loans: Non-accruing $ 8,000 $ 2,289 $ 829 $ 5,722 $ — $ 16,840 Restructured accruing 775 — — 417 1,444 2,636 Restructured non-accruing 437 1,859 — 2,728 273 5,297 Balance $ 9,212 $ 4,148 $ 829 $ 8,867 $ 1,717 $ 24,773 Unpaid principal balance in total impaired loans $ 13,805 $ 6,072 $ 829 $ 11,296 $ 2,618 $ 34,620 2019 Commercial Real Estate Total Recorded Investment in Impaired (In thousands) Commercial Commercial Commercial Commercial Average impaired loans for the period $ 7,565 $ 4,390 $ 2,052 $ 7,781 $ 1,577 $ 23,365 Contractual interest income due on impaired loans during the period $ 786 $ 258 $ 127 $ 648 $ 128 $ 1,947 Interest income on impaired loans recognized on a cash basis $ 49 $ 187 $ — $ 221 $ 8 $ 465 Interest income on impaired loans recognized on an accrual basis $ 39 $ — $ — $ 62 $ 68 $ 169 Credit Quality The following tables provide information on the credit quality of the loan portfolio under the new CECL disclosure requirements for the loan portfolio by segment at December 31 for the years indicated: 2020 Commercial Real Estate Residential Real Estate (In thousands) Commercial Commercial Commercial Commercial Residential Residential Consumer Total Analysis of non-accrual loan activity: Balance at beginning of period $ 8,437 $ 4,148 $ 829 $ 8,450 $ 12,661 $ — $ 4,107 $ 38,632 PCD loans designated as non-accrual (1) 9,544 — — 2,539 8 — 993 13,084 Loans placed on non-accrual 37,882 8,572 15,844 17,442 1,485 — 4,061 85,286 Non-accrual balances transferred to OREO — — — — (70) — — (70) Non-accrual balances charged-off (411) — — (446) (416) — (121) (1,394) Net payments or draws (10,225) (1,059) (1,629) (4,169) (2,598) — (1,521) (21,201) Non-accrual loans brought current — (100) — (883) (858) — (135) (1,976) Balance at end of period $ 45,227 $ 11,561 $ 15,044 $ 22,933 $ 10,212 $ — $ 7,384 $ 112,361 (1) Upon the adoption of the CECL standard, the Company transitioned from closed pool level accounting for PCI loans during the first quarter of 2020. Non-accrual loans are determined based on the individual loan level and aggregated for reporting. 2020 Commercial Real Estate Residential Real Estate (In thousands) Commercial Commercial Commercial Commercial Residential Residential Consumer Total Performing loans: Current $ 3,571,184 $ 1,624,265 $ 1,033,057 $ 2,238,617 $ 1,073,963 $ 182,557 $ 502,548 $ 10,226,191 30-59 days 14,046 6,390 29 4,859 16,213 — 5,275 46,812 60-89 days 4,130 — 2,843 263 2,709 62 2,047 12,054 Total performing loans 3,589,360 1,630,655 1,035,929 2,243,739 1,092,885 182,619 509,870 10,285,057 Non-performing loans: Non-accrual loans 45,227 11,561 15,044 22,933 10,212 — 7,384 112,361 Loans greater than 90 days past due 133 — — 161 480 — — 774 Restructured loans — — — 715 1,602 — — 2,317 Total non-performing loans 45,360 11,561 15,044 23,809 12,294 — 7,384 115,452 Total loans $ 3,634,720 $ 1,642,216 $ 1,050,973 $ 2,267,548 $ 1,105,179 $ 182,619 $ 517,254 $ 10,400,509 The credit quality indicators for commercial loans are developed through review of individual borrowers on an ongoing basis. Each borrower is evaluated at least annually with more frequent evaluation of more severely criticized loans. The indicators represent the rating for loans as of the date presented is based on the most recent credit review performed. These credit quality indicators are defined as follows: Pass - A pass rated credit is not adversely classified because it does not display any of the characteristics for adverse classification. Special mention - A special mention credit has potential weaknesses that deserve management’s close attention. If uncorrected, such weaknesses may result in deterioration of the repayment prospects or collateral position at some future date. Special mention assets are not adversely classified and do not warrant adverse classification. Substandard - A substandard loan is inadequately protected by the current net worth and payment capacity of the obligor or of the collateral pledged, if any. Loans classified as substandard generally have a well-defined weakness, or weaknesses, that jeopardize the liquidation of the debt. These loans are characterized by the distinct possibility of loss if the deficiencies are not corrected. Doubtful - A loan that is classified as doubtful has all the weaknesses inherent in a loan classified as substandard with added characteristics that the weaknesses make collection or liquidation in full highly questionable and improbable, on the basis of currently existing facts, conditions and values. Loss – Loans classified as a loss are considered uncollectible and of such little value that their continuing to be carried as a loan is not warranted. This classification is not necessarily equivalent to no potential for recovery or salvage value, but rather that it is not appropriate to defer a full write-off even though partial recovery may be effected in the future. The following table provides information about credit quality indicators by the year of origination: 2020 Term Loans by Origination Year Revolving (In thousands) 2020 2019 2018 2017 2016 Prior Loans Total Commercial Investor R/E: Pass $ 910,426 $ 763,214 $ 448,406 $ 448,698 $ 469,077 $ 498,384 $ 33,531 $ 3,571,736 Special Mention 11,044 — 4,879 833 269 27 — 17,052 Substandard 589 4,245 13,649 20,619 673 6,157 — 45,932 Doubtful — — — — — — — — Total $ 922,059 $ 767,459 $ 466,934 $ 470,150 $ 470,019 $ 504,568 $ 33,531 $ 3,634,720 Commercial Owner-Occupied R/E: Pass $ 285,310 $ 385,058 $ 234,578 $ 192,634 $ 204,925 $ 306,840 $ 1,664 $ 1,611,009 Special Mention 2,290 — 3,027 4,742 134 4,079 — 14,272 Substandard 1,610 4,335 2,065 465 219 8,009 — 16,703 Doubtful — — — — — 232 — 232 Total $ 289,210 $ 389,393 $ 239,670 $ 197,841 $ 205,278 $ 319,160 $ 1,664 $ 1,642,216 Commercial AD&C: Pass $ 485,631 $ 261,537 $ 149,703 $ 50,192 $ 89 $ 2,357 $ 80,764 $ 1,030,273 Special Mention 1,711 — — — — — — 1,711 Substandard 1,439 891 — 13,816 2,843 — — 18,989 Doubtful — — — — — — — — Total $ 488,781 $ 262,428 $ 149,703 $ 64,008 $ 2,932 $ 2,357 $ 80,764 $ 1,050,973 Commercial Business: Pass $ 1,244,822 $ 208,682 $ 138,861 $ 86,830 $ 34,498 $ 81,760 $ 433,016 $ 2,228,469 Special Mention 1,929 1,382 1,119 708 309 621 4,319 10,387 Substandard 2,914 4,564 3,519 1,631 2,745 3,456 1,829 20,658 Doubtful 106 995 849 36 1,284 1,852 2,912 8,034 Total $ 1,249,771 $ 215,623 $ 144,348 $ 89,205 $ 38,836 $ 87,689 $ 442,076 $ 2,267,548 Residential Mortgage: Beacon score: 660-850 $ 229,033 $ 74,054 $ 138,824 $ 172,493 $ 129,701 $ 251,065 $ — $ 995,170 600-659 4,824 7,706 10,763 11,719 8,173 21,424 — 64,609 540-599 350 1,238 5,219 2,608 4,791 10,167 — 24,373 less than 540 2,702 2,108 3,576 2,150 892 9,599 — 21,027 Total $ 236,909 $ 85,106 $ 158,382 $ 188,970 $ 143,557 $ 292,255 $ — $ 1,105,179 Residential Construction: Beacon score: 660-850 $ 112,604 $ 44,647 $ 14,543 $ 2,805 $ 1,693 $ — $ 172 $ 176,464 600-659 1,743 3,189 — — — — — 4,932 540-599 — — — — 369 — — 369 less than 540 854 — — — — — — 854 Total $ 115,201 $ 47,836 $ 14,543 $ 2,805 $ 2,062 $ — $ 172 $ 182,619 Consumer: Beacon score: 660-850 $ 2,575 $ 4,609 $ 5,112 $ 2,110 $ 2,614 $ 24,444 $ 417,737 $ 459,201 600-659 374 445 334 428 467 5,401 21,052 28,501 540-599 89 1,216 294 339 601 3,926 6,153 12,618 less than 540 751 160 525 785 532 2,826 11,355 16,934 Total $ 3,789 $ 6,430 $ 6,265 $ 3,662 $ 4,214 $ 36,597 $ 456,297 $ 517,254 Total loans $ 3,305,720 $ 1,774,275 $ 1,179,845 $ 1,016,641 $ 866,898 $ 1,242,626 $ 1,014,504 $ 10,400,509 The following section provides historical information on the credit quality of the loan portfolio under the legacy disclosure requirements: 2019 Commercial Real Estate Residential Real Estate (In thousands) Commercial Commercial Commercial Commercial Residential Residential Consumer Total Non-performing loans and assets: Non-accrual loans $ 8,437 $ 4,148 $ 829 $ 8,450 $ 12,661 $ — $ 4,107 $ 38,632 Loans 90 days past due — — — — — — — — Restructured loans 775 — — 417 1,080 — 364 2,636 Total non-performing loans 9,212 4,148 829 8,867 13,741 — 4,471 41,268 Other real estate owned 409 — 665 39 305 — 64 1,482 Total non-performing assets $ 9,621 $ 4,148 $ 1,494 $ 8,906 $ 14,046 $ — $ 4,535 $ 42,750 2019 Commercial Real Estate Residential Real Estate (In thousands) Commercial Commercial Commercial Commercial Residential Residential Consumer Past due loans: 30-59 days $ 932 $ 316 $ — $ 908 $ 14,853 $ 280 $ 2,697 $ 19,986 60-89 days — — — 370 4,541 1,334 1,517 7,762 > 90 days — — — — — — — — Total past due 932 316 — 1,278 19,394 1,614 4,214 27,748 Non-accrual loans 8,437 4,148 829 8,450 12,661 — 4,107 38,632 Loans acquired with deteriorated credit quality 9,544 — — 2,539 8 — 993 13,084 Current loans 2,150,243 1,284,213 683,181 788,752 1,117,264 144,665 457,450 6,625,768 Total loans $ 2,169,156 $ 1,288,677 $ 684,010 $ 801,019 $ 1,149,327 $ 146,279 $ 466,764 $ 6,705,232 2019 Commercial Real Estate (In thousands) Commercial Commercial Commercial Commercial Pass $ 2,146,971 $ 1,278,337 $ 683,181 $ 783,909 $ 4,892,398 Special Mention 3,189 2,284 — 2,487 7,960 Substandard 18,996 8,056 829 14,623 42,504 Doubtful — — — — — Total $ 2,169,156 $ 1,288,677 $ 684,010 $ 801,019 $ 4,942,862 2019 Residential Real Estate (In thousands) Residential Residential Consumer Performing $ 1,135,586 $ 146,279 $ 462,293 $ 1,744,158 Non-performing: 90 days past due — — — — Non-accruing 12,661 — 4,107 16,768 Restructured loans 1,080 — 364 1,444 Total $ 1,149,327 $ 146,279 $ 466,764 $ 1,762,370 The following table provides the amounts of the restructured loans at the date of restructuring for specific segments of the loan portfolio during the period indicated: For the Year Ended December 31, 2020 Commercial Real Estate (In thousands) Commercial Commercial Commercial Commercial All Other Total Troubled debt restructurings: Restructured accruing $ — $ — $ — $ 380 $ 549 $ 929 Restructured non-accruing 723 930 — 1,951 — 3,604 Balance $ 723 $ 930 $ — $ 2,331 $ 549 $ 4,533 Specific allowance $ 65 $ — $ — $ 955 $ — $ 1,020 Restructured and subsequently defaulted $ — $ — $ — $ — $ — $ — For the Year Ended December 31, 2019 Commercial Real Estate (In thousands) Commercial Commercial Commercial Commercial All Other Total Troubled debt restructurings: Restructured accruing $ 775 $ — $ — $ 170 $ 364 $ 1,309 Restructured non-accruing 789 — — 261 — 1,050 Balance $ 1,564 $ — $ — $ 431 $ 364 $ 2,359 Specific allowance $ 205 $ — $ — $ 196 $ — $ 401 Restructured and subsequently defaulted $ — $ — $ — $ — $ — $ — At December 31, 2020, TDR loans totaled $8.5 million, of which $2.3 million were accruing and $6.2 million were non-accruing. There were no commitments to lend additional funds on loans classified as TDRs as of December 31, 2020. TDR loans at December 31, 2019 totaled $7.9 million, of which $2.6 million were accruing and $5.3 million were non-accruing. Commitments to lend additional funds on TDR loans at December 31, 2019 were insignificant. During the year ended December 31, 2020, the Company restructured $4.5 million in loans that were designated as TDRs. Modifications consisted principally of interest rate concessions. No modifications resulted in the reduction of the principal in the associated loan balances. TDR loans are subject to periodic credit reviews to determine the necessity and appropriateness of an individual credit loss allowance based on the collectability of the recorded investment in the TDR loan. Loans restructured during 2020 had individual reserves of $1.0 million at December 31, 2020. For the year ended December 31, 2019, the Company restructured $2.4 million in loans. Modifications consisted principally of interest rate concessions and no modifications resulted in the reduction of the recorded investment in the associated loan balances. Loans restructured during 2019 had specific reserves of $0.4 million at December 31, 2019. For more information on the accounting policies for TDRs see Note 1. Other Real Estate Owned OREO totaled $1.5 million at December 31, 2020 and 2019, respectively. At December 31, 2020, $0.3 million of the OREO was comprised of consumer mortgage loans. There were no consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceedings were in process as of December 31, 2020.

PREMISES AND EQUIPMENT

PREMISES AND EQUIPMENT	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
PREMISES AND EQUIPMENT	PREMISES AND EQUIPMENT Presented in the following table are the components of premises and equipment at December 31: (In thousands) 2020 2019 Land $ 13,262 $ 10,160 Buildings and leasehold improvements 70,776 70,812 Equipment 49,614 46,471 Total premises and equipment 133,652 127,443 Less: accumulated depreciation and amortization (75,932) (68,828) Net premises and equipment $ 57,720 $ 58,615 Depreciation and amortization expense for premises and equipment amounted to $8.5 million, $7.2 million, and $7.2 million for each of the years ended December 31, 2020, 2019 and 2018, respectively.

LEASES

LEASES	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
LEASES	LEASES The Company leases real estate properties for its network of bank branches, financial centers and corporate offices. All of the Company’s leases are currently classified as operating. Most lease agreements include one or more options to renew, with renewal terms that can extend the original lease term from one The following table provides information regarding the Company's leases as of the dates indicated: Year Ended 2020 2019 Components of lease expense: Operating lease cost (resulting from lease payments) $ 12,453 $ 11,334 Supplemental cash flow information related to leases: Operating cash flows from operating leases $ 13,571 $ 8,704 ROU assets obtained in the exchange for lease liabilities due to: New leases $ 871 $ 399 Acquisitions $ 7,720 $ — As of December 31, 2020 December 31, 2019 Supplemental balance sheet information related to leases: Operating lease ROU assets $ 65,215 $ 69,320 Operating lease liabilities $ 74,982 $ 76,871 Other information related to leases: Weighted average remaining lease term of operating leases 9.5 years 10.4 years Weighted average discount rate of operating leases 3.04 % 3.28 % The Company added two locations from the acquisition of RPJ during the first quarter of 2020. The associated new ROU assets obtained in exchange for lease obligations totaled $0.3 million. On April 1, 2020, in conjunction with the acquisition of Revere, the Company added 15 additional operating leases (at 12 locations), one of which is expected to commence operations during the first quarter of 2021. The associated new ROU assets of $7.4 million obtained in exchange for lease obligations of $8.7 million was recorded at the close of the acquisition. The ROU assets recorded at acquisition included $1.1 million for acquisition related unfavorable fair value marks and a tenant allowance of $0.2 million. During the three months ended June 30, 2020, subsequent to and resulting from the acquisition, the Company determined that due to market overlap and other synergies, the Company would more likely than not terminate seven of the acquired leases, comprised of six branch locations and one office space location. The decision resulted in an impairment charge of $2.3 million, which was recorded to merger and acquisition expense in the Consolidated Statements of Income during the second quarter of 2020. The Company estimated the fair value of the leases to be equal to the cash payments remaining between the impairment date and the anticipated abandonment date. As of December 31, 2020, the maturities of the Company’s operating lease liabilities were as follows: (In thousands) Amount Maturity: One year $ 12,490 Two years 10,946 Three years 10,851 Four years 9,063 Five years 7,347 Thereafter 37,382 Total undiscounted lease payments 88,079 Less: Present value discount (13,097) Lease Liability $ 74,982

GOODWILL AND OTHER INTANGIBLE A

GOODWILL AND OTHER INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND OTHER INTANGIBLE ASSETS	GOODWILL AND OTHER INTANGIBLE ASSETS The gross carrying amounts and accumulated amortization of intangible assets and goodwill are presented at December 31 in the following table: 2020 Weighted 2019 Weighted Gross Net Average Gross Net Average Carrying Accumulated Carrying Remaining Carrying Accumulated Carrying Remaining (Dollars in thousands) Amount Amortization Amount Life Amount Amortization Amount Life Amortizing intangible assets: Core deposit intangibles $ 29,038 $ (7,969) $ 21,069 8.4 years $ 10,678 $ (3,689) $ 6,989 8.0 years Other identifiable intangibles 13,906 (2,454) 11,452 10.7 years 1,478 (626) 852 9.7 years Total amortizing intangible assets $ 42,944 $ (10,423) $ 32,521 $ 12,156 $ (4,315) $ 7,841 Goodwill $ 370,223 $ 370,223 $ 347,149 $ 347,149 The following table presents the net carrying amount of goodwill by segment for the periods indicated: (In thousands) Community Investment Balance December 31, 2018 $ 331,173 $ 6,788 $ 9,188 $ 347,149 No Activity — — — — Balance December 31, 2019 331,173 6,788 9,188 347,149 Acquisition of Rembert Pendleton Jackson — — 22,559 22,559 Acquisition of Revere Bank 515 — — 515 Balance December 31, 2020 $ 331,688 $ 6,788 $ 31,747 $ 370,223 The following table presents the estimated future amortization expense for amortizing intangible assets within the years ending December 31: (In thousands) Amount 2021 $ 6,600 2022 5,844 2023 5,089 2024 4,333 2025 3,567 Thereafter 7,088 Total amortizing intangible assets $ 32,521

DEPOSITS

DEPOSITS	12 Months Ended
	Dec. 31, 2020
Deposits [Abstract]
DEPOSITS	DEPOSITS The following table presents the composition of deposits at December 31 for the years indicated: (In thousands) 2020 2019 Noninterest-bearing deposits $ 3,325,547 $ 1,892,052 Interest-bearing deposits: Demand 1,292,164 836,433 Money market savings 3,339,645 1,839,593 Regular savings 418,051 329,919 Time deposits of less than $100,000 509,919 463,431 Time deposits greater than $100,000 and less than $250,000 670,717 682,936 Time deposits of $250,000 or more 477,026 395,955 Total interest-bearing deposits 6,707,522 4,548,267 Total deposits $ 10,033,069 $ 6,440,319 Demand deposit overdrafts reclassified as loan balances were $13.1 million and $1.4 million at December 31, 2020 and 2019, respectively. Overdraft charge-offs and recoveries are reflected in the allowance for credit losses. The following table presents the maturity schedule for time deposits maturing within years ending December 31: (In thousands) Amount 2021 $ 1,208,915 2022 275,872 2023 84,093 2024 73,859 2025 14,745 Thereafter 178 Total time deposits $ 1,657,662 The Company's time deposits of $100,000 to $250,000 represented 6.7% of total deposits and time deposits of $250,000 or more represented 4.8% of total deposits at December 31, 2020 and are presented by maturity in the following table: Months to Maturity (In thousands) 3 or Less Over 3 to 6 Over 6 to 12 Over 12 Total Time deposits - $100,000 to $250,000 $ 211,006 $ 127,934 $ 139,133 $ 192,644 $ 670,717 Time deposits - $250,000 or more $ 111,332 $ 115,678 $ 140,231 $ 109,785 $ 477,026 Interest expense on time deposits of $100,000 to $250,000 amounted to $8.1 million, $10.8 million, and $9.5 million and interest expense on time deposits of $250,000 of more amounted to $10.7 million, $13.0 million, and $3.0 million for the years ended December 31, 2020, 2019 and 2018, respectively. Deposits received in the ordinary course of business from the directors and officers of the Company amounted to $73.4 million and $29.9 million for the years ended December 31, 2020 and 2019, respectively.

BORROWINGS

BORROWINGS	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
BORROWINGS	BORROWINGS Subordinated Debt On November 5, 2019, the Company completed an offering of $175.0 million aggregate principal amount Fixed to Floating Rate Subordinated Notes due in 2029. The notes bear a fixed interest rate of 4.25% per year through November 14, 2024. Beginning November 15, 2024, the interest rate will become a floating rate equal to three-month LIBOR, or an alternative benchmark rate as determined pursuant to the terms of the indenture for the notes in the event LIBOR has been discontinued by November 15, 2024, plus 262 basis points through the remaining maturity or early redemption date of the notes. The interest will be paid in arrears semi-annually during the fixed rate period and quarterly during the floating rate period. The Company incurred $2.9 million of debt issuance costs which are being amortized through the contractual life of the debt. The entire amount of subordinated debt is considered Tier 2 capital under current regulatory guidelines. In conjunction with the acquisition of WashingtonFirst Bankshares, Inc. (WashingtonFirst"), the Company assumed $25.0 million in subordinated debt. The associated purchase premium at acquisition was $2.2 million, the premium is amortized over the contractual life of the obligation. The subordinated debt has a maturity of ten years, is due in full on October 15, 2025, and was non-callable through October 15, 2020. The subordinated debt held a fixed interest rate of 6.00% per annum through October 5, 2020 at which point the rate became variable at the three-month LIBOR plus 457 basis points, payable quarterly. As of December 31, 2020, the effective variable rate was 4.81%. Under regulatory capital guidelines subordinated debt begins to phase out of Tier 2 capital qualification, on an annual straight-line basis, when there are five years remaining until the subordinated debt matures. The WashingtonFirst subordinated debt has less than five years but more than four years remaining until it matures, and therefore, as of December 31, 2020, $20.0 million of the subordinated debt is considered Tier 2 capital under current regulatory guidelines. Also in conjunction with the acquisition of WashingtonFirst, the Company assumed $10.3 million in callable junior subordinated debt securities with an associated purchase premium at acquisition of $0.1 million. During the first quarter of 2020, the Company redeemed all $10.3 million of the outstanding principal balance of the callable junior subordinated debt securities. In conjunction with the acquisition of Revere, the Company assumed $31.0 million in subordinated debt with an associated purchase premium at acquisition of $0.2 million, which will be amortized through the call date. The subordinated debt has a ten year term, maturing on September 30, 2026, is non-callable until September 30, 2021, and currently bears a fixed interest rate of 5.625% per annum, payable semi-annually. Beginning on October 1, 2021, the interest rate resets quarterly to an amount equal to three-month LIBOR plus 441 basis points. The entire amount of the subordinated debt is considered Tier 2 capital under current regulatory guidelines. The following table provides information on subordinated debentures for the period indicated: (In thousands) 2020 2019 Fixed to floating rate sub debt, 4.25% $ 175,000 $ 175,000 WashingtonFirst sub debt, 4.81% 25,000 25,000 Revere fixed to floating rate sub debt, 5.625% 31,000 — Total Sub debt 231,000 200,000 Less: WashingtonFirst and Revere sub debt held as investments by Sandy Spring (3,000) — Add: Purchase accounting premium 1,669 1,894 Less: Debt issuance costs (2,581) (2,885) Net sub debt 227,088 199,009 WashingtonFirst callable junior subordinated debt — 10,310 Add: Purchase accounting premium — 87 Net WashingtonFirst callable junior subordinated debt — 10,397 Long-term borrowings $ 227,088 $ 209,406 Other Borrowings Information relating to retail repurchase agreements and federal funds purchased is presented in the following table at and for the years ending December 31: 2020 2019 2018 (Dollars in thousands) Amount Rate Amount Rate Amount Rate End of period: Retail repurchase agreements $ 153,157 0.11 % $ 138,605 0.58 % $ 137,429 0.51 % Federal funds purchased 390,000 0.10 75,000 1.62 — — Average for the year: Retail repurchase agreements $ 142,283 0.32 % $ 134,070 0.54 % $ 142,938 0.34 % Federal funds purchased 367,240 0.41 17,373 2.43 — — Maximum month-end balance: Retail repurchase agreements $ 153,157 $ 152,685 $ 154,435 Federal funds purchased 921,289 75,000 — The Company pledges U.S. Agencies securities, based upon their market values, as collateral for greater than 102.5% of the principal of its retail repurchase agreements. At December 31, 2020, the Company had an available line of credit with the FHLB under which its borrowings are limited to $3.0 billion based on pledged collateral at prevailing market interest rates with $379.1 million borrowed against it at December 31, 2020. At December 31, 2019, lines of credit totaled $2.4 billion based on pledged collateral with $513.8 million borrowed against the line. Under a blanket lien, the Company has pledged qualifying residential mortgage loans amounting to $1.0 billion, commercial real estate loans amounting to $2.8 billion, home equity lines of credit (“HELOC”) amounting to $226.2 million and multifamily loans amounting to $237.6 million at December 31, 2020 as collateral under the borrowing agreement with the FHLB. At December 31, 2019, the Company had pledged collateral of qualifying mortgage loans of $1.0 billion, commercial real estate loans of $1.9 billion, HELOC loans of $266.8 million and multifamily loans of $109.7 million under the FHLB borrowing agreement. The Company also had secured lines of credit available from the Federal Reserve and correspondent banks of $276.2 million and $463.3 million at December 31, 2020 and 2019, respectively, collateralized by loans. In addition, the Company had unsecured lines of credit with correspondent banks of $1.1 billion and $730.0 million at December 31, 2020 and 2019. At December 31, 2020, the total outstanding borrowings against these unsecured lines of credit was $390.0 million. At December 31, 2020, the Company did not have any borrowings outstanding of the $1.1 billion available to borrow under the Paycheck Protection Program Liquidity Facility ("PPPLF"). Amounts borrowed under the PPPLF are required to be repaid as PPP loans are repaid or forgiven. Advances from the FHLB and the respective maturity schedule at December 31 for the years indicated consisted of the following: 2020 2019 (Dollars in thousands) Amounts Weighted Average Amounts Weighted Average Maturity: One year $ 230,243 2.39 % $ 134,167 2.13 % Two years 76,332 2.37 230,445 2.39 Three years 72,500 3.12 76,665 2.37 Four years — — 72,500 3.12 Five years — — — — After five years — — — — Total advances from FHLB $ 379,075 2.52 $ 513,777 2.42

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS’ EQUITY The Company’s Articles of Incorporation authorize 100,000,000 shares of capital stock (par value $1.00 per share). Issued shares have been classified as common stock. The Articles of Incorporation provide that remaining unissued shares may later be designated as either common or preferred stock. The Company had a director stock purchase plan (the “Director Plan”) which commenced on May 1, 2004. Under the Director Plan, members of the board of directors may elect to use a portion (minimum 50%) of their annual retainer fee to purchase shares of Company stock. The Company reserved 45,000 authorized but unissued shares of common stock for purchase under the plan. Purchases were made at the fair market value of the stock on the purchase date. The Director Plan expired during 2020 and was not reauthorized. At December 31, 2020 there were 24,424 shares that remained unissued. The Company maintains an employee stock purchase plan (the “Purchase Plan”) that enables employees to purchase up to $25,000 of Company common stock each year at a discount. The Purchase Plan, which was initially authorized on July 1, 2011, was amended and restated as of November 18, 2020. As part of the amendment and restatement, an additional 700,000 shares of common stock were reserved to be issued, which is in addition to the 300,000 shares of common stock authorized for purchase under the previous version of the Purchase Plan. Under the Purchase Plan, shares are purchased at 85% of the lower of the fair market value of the common stock on the offering date or the purchase date, as defined in the Purchase Plan. Contributions are made through monthly payroll deductions of not less than 1% or more than 10% of cash compensation paid in the month. The Purchase Plan is administered by a committee of at least three directors appointed by the board of directors. At December 31, 2020, there were 707,153 shares available for issuance under this Purchase Plan. In December 2020, the Company's board of directors authorized a stock repurchase plan that permits the repurchase of up to 2,350,000 shares of common stock. No shares of common stock have been repurchased under this plan. Under the previous stock repurchase plan that was approved in 2018 and expired in December 2020, the Company was authorized to repurchase up to 1,800,000 shares. During 2020, the Company repurchased 820,328 common shares for the total cost of $25.7 million. Cumulatively under the program, as of December 31, 2020, the Company repurchased and retired 1,488,519 shares of its common stock at an average price of $33.58 per share for a total cumulative cost of $50.0 million . The Company has a dividend reinvestment plan that is sponsored and administered by Computershare Shareholder Services ("Computershare") as independent agent, which enables current shareholders as well as first-time buyers to purchase and sell common stock of Sandy Spring Bancorp, Inc. directly through Computershare. Participants may reinvest cash dividends and make periodic supplemental cash payments to purchase additional shares. Bank and bank holding company regulations, as well as Maryland law, impose certain restrictions on dividend payments by the Bank, as well as restrictions on extensions of credit and transfers of assets between the Bank and the Company. At December 31, 2020, the Bank could have paid additional dividends of $144.9 million to its parent company without regulatory approval. There were no loans outstanding between the Bank and the Company at December 31, 2020 and 2019, respectively.

SHARE BASED COMPENSATION

SHARE BASED COMPENSATION	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
SHARE BASED COMPENSATION	SHARE BASED COMPENSATION At December 31, 2020, the Company had two share based compensation plans in existence, the 2005 Omnibus Stock Plan (“Omnibus Stock Plan”) and the 2015 Omnibus Incentive Plan (“Omnibus Incentive Plan”). The Omnibus Stock Plan expired during the second quarter of 2015 but has outstanding options that may still be exercised. The Omnibus Incentive Plan is described in the following paragraph. The Company’s Omnibus Incentive Plan was approved on May 6, 2015 and provides for the granting of incentive stock options, non-qualifying stock options, stock appreciation rights, restricted stock grants, restricted stock units and performance share units to selected directors and employees on a periodic basis at the discretion of the Company’s board of directors. The Omnibus Incentive Plan authorizes the issuance of up to 1,500,000 shares of common stock, of which 914,502 shares are available for issuance at December 31, 2020, has a term of ten years, and is administered by a committee of at least three directors appointed by the board of directors. Options granted under the plan have an exercise price which may not be less than 100% of the fair market value of the common stock on the date of the grant and must be exercised within seven to ten years from the date of grant depending on the terms of the grant agreement. The exercise price of stock options must be paid for in full in cash or shares of common stock, or a combination of both. The board committee has the discretion when making a grant of stock options to impose restrictions on the shares to be purchased upon the exercise of such options. The Company generally issues authorized but previously unissued shares to satisfy option exercises. The fair values of all of the options granted for the periods indicated have been estimated using a binomial option-pricing model with the weighted-average assumptions for the years ended December 31 are presented in the following table: 2020 2019 2018 Dividend yield — % — % 2.64 % Weighted average expected volatility — % — % 39.13 % Weighted average risk-free interest rate — % — % 2.61 % Weighted average expected lives (in years) 0 0 5.61 years Weighted average grant-date fair value $ — $ — $ 11.73 The dividend yield is based on estimated future dividend yields. The risk-free rate for periods within the contractual term of the share option is based on the U.S. Treasury yield curve in effect at the time of the grant. Expected volatility is generally based on historical volatility. The expected term of share options granted is generally derived from historical experience. The Company recognizes forfeitures as they occur. Compensation expense is recognized on a straight-line basis over the vesting period of the respective stock option, restricted stock, restricted stock unit grants or performance share units. Compensation expense of $3.9 million, $2.9 million, and $2.5 million was recognized for the years ended December 31, 2020, 2019 and 2018, respectively, related to the awards of stock options, restricted stock grants, restricted stock unit grants and performance share unit grants. The intrinsic value for the stock options exercised was $0.4 million, $0.2 million, and $0.4 million in the years ended December 31, 2020, 2019 and 2018, respectively. The total of unrecognized compensation cost related to stock options was immaterial at December 31, 2020. That cost is expected to be recognized over a weighted average period of approximately 0.3 years. The fair value of the options vested during the years ended December 31, 2020, 2019 and 2018, was $0.1 million, $0.2 million, and $0.1 million, respectively. The total of unrecognized compensation cost related to restricted stock awards, restricted stock unit grants, and performance share unit grants was approximately $8.0 million at December 31, 2020. That cost is expected to be recognized over a weighted average period of approximately 2.6 years. During the year ended December 31, 2020, the Company granted 246,015 restricted shares, restricted stock units and performance share units under the Omnibus Incentive Plan, of which 44,905 units are subject to achievement of certain performance conditions measured over a three-year performance period and 201,110 of restricted shares or units subject to a three- or five-year vesting schedule. Due to the assumption of stock options held as of the Acquisition Date by Revere employees, the Company issued 395,298 stock options at a weighted average grant-date fair value of $9.14 during the second quarter of 2020. The fair value of the options issued were considered part of the consideration transferred and were therefore recorded as an adjustment to goodwill. See Note 2 for additional information on the acquisition of Revere. The Company did not grant any stock options under the Omnibus Incentive Plan during the year ended December 31, 2020 or 2019. A summary of share option activity for the period indicated is reflected in the following table: Number Weighted Average Exercise Weighted Average Contractual Remaining Life (Years) Aggregate Intrinsic Balance at January 1, 2020 65,279 $ 31.34 $ 485 Granted — $ — Converted options from Revere acquisition 395,298 $ 12.27 Exercised (26,063) $ 12.10 $ 398 Forfeited (765) $ 39.02 Expired (3,711) $ 30.46 Balance at December 31, 2020 430,038 $ 14.97 3.0 years $ 6,828 Exercisable at December 31, 2020 425,274 $ 14.71 3.0 years $ 6,828 A summary of the activity for the Company’s restricted stock for the period indicated is presented in the following table: (In dollars, except share data): Number Weighted Average Grant-Date Fair Value Restricted stock at January 1, 2020 226,502 $ 35.43 Granted 246,015 $ 25.82 Vested (66,533) $ 34.38 Forfeited (14,301) $ 37.47 Restricted stock at December 31, 2020 391,683 $ 29.50

PENSION, PROFIT SHARING, AND OT

PENSION, PROFIT SHARING, AND OTHER EMPLOYEE BENEFIT PLANS	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
PENSION, PROFIT SHARING, AND OTHER EMPLOYEE BENEFIT PLANS	PENSION, PROFIT SHARING, AND OTHER EMPLOYEE BENEFIT PLANS Defined Benefit Pension Plan The Company has a qualified, noncontributory, defined benefit pension plan (the “Pension Plan”) covering substantially all employees. All benefit accruals for employees were frozen as of December 31, 2007 based on past service and thus future salary increases and additional years of service will no longer affect the defined benefit provided by the Pension Plan although additional vesting may continue to occur. The Company's funding policy is to contribute amounts to the Pension Plan sufficient to meet the minimum funding requirements of the Employee Retirement Income Security Act of 1974 (“ERISA”), as amended. In addition, the Company contributes additional amounts as it deems appropriate based on benefits attributed to service prior to the date of the Pension Plan freeze. The Pension Plan invests primarily in a diversified portfolio of managed fixed income and equity funds. The Pension Plan’s funded status at December 31 is as follows: (In thousands) 2020 2019 Reconciliation of Projected Benefit Obligation: Projected obligation at January 1 $ 45,497 $ 40,152 Interest cost 1,437 1,609 Actuarial loss 290 371 Benefit payments (1,470) (1,695) Increase related to change in assumptions 6,672 5,060 Projected obligation at December 31 52,426 45,497 Reconciliation of Fair Value of Plan Assets: Fair value of plan assets at January 1 43,457 37,772 Actual return on plan assets 6,370 7,195 Contribution — 185 Benefit payments (1,470) (1,695) Fair value of plan assets at December 31 $ 48,357 $ 43,457 Funded status at December 31 $ (4,069) $ (2,040) Accumulated benefit obligation at December 31 $ 52,426 $ 45,497 Unrecognized net actuarial loss $ 12,719 $ 11,177 Net periodic pension cost not yet recognized $ 12,719 $ 11,177 Weighted average assumptions used to determine benefit obligations at December 31 are presented in the following table: 2020 2019 2018 Discount rate 2.50% 3.25% 4.15% Rate of compensation increase N/A N/A N/A The components of net periodic benefit cost for the years ended December 31 are presented in the following table: (In thousands) 2020 2019 2018 Interest cost on projected benefit obligation $ 1,437 $ 1,609 $ 1,540 Expected return on plan assets (1,821) (1,647) (1,861) Recognized net actuarial loss 874 1,059 1,000 Net periodic benefit cost $ 490 $ 1,021 $ 679 Weighted average assumptions used to determine net periodic benefit cost for years ended December 31 are presented in the following table: 2020 2019 2018 Discount rate 3.25% 4.15% 3.65% Expected return on plan assets 4.75% 5.00% 5.00% Rate of compensation increase N/A N/A N/A The expected rate of return on assets of 4.75% reflects the Pension Plan’s predominant investment of assets in fixed income mutual funds and was developed as a weighted average rate based on the target asset allocation of the Plan. Key economic inputs used included future inflation, economic growth, and interest rate environment. The following table reflects the components of the net unrecognized benefits costs that is reflected in accumulated other comprehensive income/ (loss) for the periods indicated. Additions/ reductions represent the change in the unrecognized actuarial gain/ loss during the period. Reclassifications represent the portion of the unrecognized benefits that are recognized each period as a component of the net periodic benefit cost. (In thousands) Unrecognized Net Included in accumulated other comprehensive loss at January 1, 2018 $ 12,487 Reductions during the year 3,914 Reclassifications due to recognition as net periodic pension cost (1,000) Increase related to change in assumptions (3,049) Included in accumulated other comprehensive loss as of December 31, 2018 12,352 Additions during the year (5,176) Reclassifications due to recognition as net periodic pension cost (1,059) Decrease related to change in assumptions 5,060 Included in accumulated other comprehensive loss as of December 31, 2019 11,177 Reductions during the year (4,256) Reclassifications due to recognition as net periodic pension cost (874) Increase related to change in assumptions 6,672 Included in accumulated other comprehensive loss as of December 31, 2020 12,719 Applicable tax effect (3,249) Included in accumulated other comprehensive loss net of tax effect at December 31, 2020 $ 9,470 Amount expected to be recognized as part of net periodic pension cost in the next fiscal year $ 931 There are no plan assets expected to be returned to the employer in the next twelve months. The following items have not yet been recognized as a component of net periodic benefit cost at December 31: (In thousands) 2020 2019 2018 Net actuarial loss $ 12,719 $ 11,177 $ 12,352 Net periodic benefit cost not yet recognized $ 12,719 $ 11,177 $ 12,352 Pension Plan Assets The Company’s Pension Plan weighted average allocations at December 31 are presented in the following table: 2020 2019 Asset Category: Equity Securities Mutual Funds 11.6 % 10.4 % Fixed Income Mutual Funds 88.4 % 89.6 % Total pension plan assets 100.0 % 100.0 % The Company has a written investment policy approved by the board of directors that governs the investment of the defined benefit pension fund trust portfolio. The investment policy is designed to provide limits on risk that is undertaken by the investment managers both in terms of market volatility of the portfolio and the quality of the individual assets that are held in the portfolio. The investment policy statement focuses on the following areas of concern: preservation of capital, diversification, risk tolerance, investment duration, rate of return, liquidity, and investment management costs. The Company has constituted the Retirement Plans Investment Committee (“RPIC”) in part to monitor the investments of the Pension Plan as well as to recommend to executive management changes in the Investment Policy Statement which governs the Pension Plan’s investment operations. These recommendations include asset allocation changes based on a number of factors including the investment horizon for the Pension Plan. The Company uses outside third parties to advise RPIC on the Pension Plan’s investment matters. Investment strategies and asset allocations are based on careful consideration of Pension Plan liabilities, the Pension Plan’s funded status and the Company’s financial condition. Investment performance and asset allocation are measured and monitored on an ongoing basis. Management allocates plan assets towards fixed income securities in order to align expected cash outflows with its funding source. This asset allocation has been set after taking into consideration the Pension Plan’s current frozen status and the possibility of partial plan terminations over the intermediate term. The Pension Plan’s asset allocation remained consistent during the current year. Market volatility risk is controlled by limiting the asset allocation of the most volatile asset class, equities, to no more than 70% of the portfolio and by ensuring that there is sufficient liquidity to meet distribution requirements from the portfolio without disrupting long-term assets. Diversification of the equity portion of the portfolio is controlled by limiting the value of any initial acquisition so that it does not exceed 5% of the market value of the portfolio when purchased. The policy requires the sale of any portion of an equity position when its value exceeds 10% of the portfolio. Fixed income market volatility risk is managed by limiting the term of fixed income investments to five years. Fixed income investments must carry an “A” or better rating by a recognized credit rating agency. Corporate debt of a single issuer may not exceed 10% of the market value of the portfolio. The investment in derivative instruments such as “naked” call options, futures, commodities, and short selling is prohibited. Investment in equity index funds and the writing of “covered” call options (a conservative strategy to increase portfolio income) are permitted. Foreign currency-denominated debt instruments are not permitted. At December 31, 2020, management is of the opinion that there are no significant concentrations of risk in the assets of the plan with respect to any single entity, industry, country, commodity or investment fund that are not otherwise mitigated by the Federal Deposit Insurance Corporation ("FDIC") insurance available to the participants of the Pension Plan and collateral pledged for any such amount that may not be covered by FDIC insurance. Investment performance is measured against industry accepted benchmarks. The risk tolerance and asset allocation limitations imposed by the policy are consistent with attaining the rate of return assumptions used in the actuarial funding calculations. The RPIC committee meets quarterly to review the activities of the investment managers to ensure adherence with the Investment Policy Statement. Fair Values The fair values of the Company’s Pension Plan assets by asset category at December 31 are presented in the following tables: 2020 (In thousands) Quoted Prices in Active Markets for Significant Other Significant Total Asset Category: Mutual funds: Large cap U.S. equity funds $ 2,779 $ 543 $ — $ 3,322 Small/Mid cap U.S. equity funds — 1,124 — 1,124 International equity funds 1,183 — — 1,183 Short-term fixed income funds — 4,299 — 4,299 Fixed income funds 10,724 27,705 — 38,429 Total mutual funds 14,686 33,671 — 48,357 Total pension plan assets $ 14,686 $ 33,671 $ — $ 48,357 2019 (In thousands) Quoted Prices In Active Markets for Significant Other Significant Total Asset Category: Mutual funds: Large cap U.S. equity funds $ 1,855 $ 919 $ — $ 2,774 Small/Mid cap U.S. equity funds — 847 — 847 International equity funds 894 — — 894 Short-term fixed income funds — 3,688 — 3,688 Fixed income funds 8,769 26,485 — 35,254 Total mutual funds 11,518 31,939 — 43,457 Total pension plan assets $ 11,518 $ 31,939 $ — 43,457 Contributions The decision as to whether or not to make a plan contribution and the amount of any such contribution is dependent on a number of factors. Such factors include the investment performance of the plan assets in the current economy and, since the Pension Plan is currently frozen, the remaining investment horizon of the Pension Plan. After consideration of these factors, the Company made no contributions in 2020. Management continues to monitor the funding level of the Pension Plan and may make contributions as necessary during 2021. Estimated Future Benefit Payments Benefit payments, which reflect expected future service, as appropriate, that are expected to be paid for the years ending December 31 are presented in the following table: (In thousands) Pension Benefits 2021 $ 3,340 2022 2,590 2023 2,190 2024 3,260 2025 2,410 Thereafter 15,270 Sandy Spring Bank 401(k) Plan The Sandy Spring Bank 401(k) Plan (“the 401(k)”) is voluntary and covers all eligible employees after 90 days of service. The 401(k) provides that employees contributing to the 401(k) receive a matching contribution of 100% of the first 4% of compensation and 50% of the next 2% of compensation subject to employee contribution limitations. The Company matching contribution vests immediately. The 401(k) permits employees to purchase shares of the Company’s common stock with their 401(k) contributions, Company match, and other contributions under the 401(k). The Company’s matching contribution to the 401(k) are included in salaries and employee benefits in non-interest expenses in the Consolidated Statements of Income totaled $5.3 million, $4.1 million, and $2.8 million in 2020, 2019 and 2018, respectively. Executive Incentive Retirement Plan The Executive Incentive Retirement Plan ("Executive Plan") is a non-qualified deferred compensation defined contribution plan that provides for contributions to be made to the participants’ plan accounts based on the attainment of a level of financial performance compared to a selected group of peer banks. This level of performance is determined annually by the board of directors. Benefit costs related to the Executive Plan included in salaries and employee benefits in non-interest expenses in the Consolidated Statements of Income for 2020, 2019 and 2018 were $0.6 million, $0.5 million, and $0.4 million, respectively.

OTHER NON-INTEREST INCOME AND O

OTHER NON-INTEREST INCOME AND OTHER NON-INTEREST EXPENSE	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
OTHER NON-INTEREST INCOME AND OTHER NON-INTEREST EXPENSE	OTHER NON-INTEREST INCOME AND OTHER NON-INTEREST EXPENSE Selected components of other non-interest income and other non-interest expense for the years ended December 31 are presented in the following table: (In thousands) 2020 2019 2018 Letter of credit fees $ 710 $ 389 $ 611 Extension fees 1,967 1,287 873 Swap fee income 1,607 1,932 — Loan prepayment penalties 961 404 594 Other income 3,976 4,768 5,048 Total other non-interest income $ 9,221 $ 8,780 $ 7,126 (In thousands) 2020 2019 2018 Postage and delivery $ 1,624 $ 1,502 $ 1,439 Communications 2,729 2,414 2,610 Loss on FHLB redemption 5,928 — — Mortgage processing expense, net 1,381 817 53 Online services 1,591 1,375 1,263 Provision for credit losses on unfunded loan commitments 1,576 — — Franchise taxes 1,574 1,307 2,143 Insurance 1,311 1,113 1,043 Card transaction expense 1,083 1,031 961 Office supplies 912 957 951 Other expenses 10,894 9,910 9,029 Total other non-interest expense $ 30,603 $ 20,426 $ 19,492

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The following table provides the components of income tax expense for the years ended December 31: (In thousands) 2020 2019 2018 Current income taxes: Federal $ 43,115 $ 28,404 $ 18,615 State 13,785 6,598 7,183 Total current 56,900 35,002 25,798 Deferred income taxes: Federal (22,793) 234 4,808 State (6,636) 1,192 1,218 Total deferred (29,429) 1,426 6,026 Total income tax expense $ 27,471 $ 36,428 $ 31,824 The Company does not have uncertain tax positions that are deemed material, and did not recognize any adjustments for unrecognized tax benefits. The Company is subject to U.S. federal income tax and income tax in various state jurisdictions. All tax years ending after December 31, 2016 are open to examination. The District of Columbia is currently conducting a routine tax exam for the tax years 2017-2019. No findings have been issued at this time and the Company does not expect any material adjustments from this exam. Temporary differences between the amounts reported in the financial statements and the tax bases of assets and liabilities result in deferred taxes. Deferred tax assets and liabilities, shown as the sum of the appropriate tax effect for each significant type of temporary difference, are presented in the following table at December 31 for the years indicated: (In thousands) 2020 2019 Deferred tax assets: Allowance for credit losses $ 42,231 $ 14,287 Lease liability 19,192 19,616 Fair value acquisition adjustments — 1,322 Employee benefits 6,108 4,535 Unrealized losses on pension plan 3,249 2,845 Deferred loan fees and costs 4,486 471 Equity based compensation 1,856 659 Losses on other real estate owned 203 201 Other than temporary impairment 75 76 Loan and deposit premium/discount 1,081 1,422 Reserve for recourse loans 546 166 Net operating loss carryforward 1,475 916 Other 181 159 Gross deferred tax assets 80,683 46,675 Valuation allowance (1,479) (880) Net deferred tax asset 79,204 45,795 Deferred tax liabilities: Right of use asset (16,693) (17,688) Unrealized gains on investments available-for-sale (9,684) (1,379) Pension plan costs (2,211) (2,373) Depreciation (2,950) (2,744) Intangible assets (6,894) (3,338) Bond accretion (195) (322) Section 481 adjustments (669) (1,335) Fair value acquisition adjustments (555) — Other (567) (585) Gross deferred tax liabilities (40,418) (29,764) Net deferred tax asset $ 38,786 $ 16,031 The Company has approximately $23.0 million of state net operating loss carryover which begins to expire in 2032. The Company believes that it is more likely than not that the future benefit from the state net operating loss carryover on $19.9 million will not be realized. As such, there is a valuation allowance on the deferred tax assets of the jurisdictions in which those net operating losses relate. The reconcilements between the statutory federal income tax rate and the effective rate for the years ended December 31 are presented in the following table: (Dollars in thousands) 2020 2019 2018 Amount Percentage of Amount Percentage of Amount Percentage of Income tax expense at federal statutory rate $ 26,130 21.0 % $ 32,101 21.0 % $ 27,865 21.0 % Increase/ (decrease) resulting from: Tax exempt income, net (2,472) (2.0) (2,101) (1.4) (2,427) (1.8) Bank-owned life insurance (567) (0.5) (665) (0.4) (909) (0.7) State income taxes, net of federal income tax benefits 5,648 4.5 6,154 4.0 6,637 5.0 Federal tax law change (1,764) (1.4) — — — — Other, net 496 0.5 939 0.6 658 0.5 Total income tax expense and rate $ 27,471 22.1 % $ 36,428 23.8 % $ 31,824 24.0 % Under the CARES Act, net operating losses arising in tax years beginning after December 31, 2017, and before January 1, 2021 can be carried back five tax years preceding the tax year in which the loss originated. During the current year, the Company utilized net operating losses acquired as a part of the 2018 WashingtonFirst acquisition. Following the passage of the CARES Act, the Company carried back WashingtonFirst's 2018 net operating loss to tax years 2013 through 2015. As a result, the Company recorded a tax benefit of $1.8 million due to the federal statutory rates for the 2013, 2014 and 2015 tax years being higher than the 2018 tax year.

NET INCOME PER COMMON SHARE

NET INCOME PER COMMON SHARE	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
NET INCOME PER COMMON SHARE	NET INCOME PER COMMON SHARE The calculation of net income per common share for the years ended December 31 is presented in the following table: (Dollars and amounts in thousands, except per share data) 2020 2019 2018 Net income $ 96,953 $ 116,433 $ 100,864 Less: Distributed and undistributed earnings allocated to participating securities (783) (762) (579) Net income attributable to common shareholders $ 96,170 $ 115,671 $ 100,285 Total weighted average outstanding shares 44,312 35,797 35,707 Less: Weighted average participating securities (365) (235) (205) Basic weighted average common shares 43,947 35,562 35,502 Dilutive weighted average common stock equivalents 185 56 21 Diluted weighted average common shares 44,132 35,618 35,523 Basic net income per common share $ 2.19 $ 3.25 $ 2.82 Diluted net income per common share $ 2.18 $ 3.25 $ 2.82 Anti-dilutive shares 17 9 7

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS)	ACCUMULATED OTHER COMPREHENSIVE INCOME/ (LOSS)Comprehensive income/ (loss) is defined as net income plus transactions and other occurrences that are the result of non-owner changes in equity. For financial statements presented for the Company, non-owner changes are comprised of unrealized gains or losses on available-for-sale debt securities and any pension liability adjustments and do not have an impact on the Company’s net income. Realized gains and losses on available-for-sale debt securities and the amortization of net periodic benefit cost impact the Company's net income as discussed in the tables on the following page. The following table presents the activity in net accumulated other comprehensive income/ (loss) for the periods indicated: Unrealized Gains/ Balance at January 1, 2018 $ 687 $ (7,544) $ (6,857) Period change, net of tax (7,465) 45 (7,420) Reclassification of tax effects from other comprehensive income 148 (1,625) (1,477) Balance at December 31, 2018 (6,630) (9,124) (15,754) Period change, net of tax 10,630 792 11,422 Balance at December 31, 2019 4,000 (8,332) (4,332) Period change, net of tax 24,175 (1,138) 23,037 Balance at December 31, 2020 $ 28,175 $ (9,470) $ 18,705 The following table provides the information on the reclassification adjustments out of accumulated other comprehensive income/ (loss) for the periods indicated: Year Ended December 31, (In thousands) 2020 2019 2018 Unrealized gains/ (losses) on investments available-for-sale: Affected line item in the Consolidated Statements of Income: Investment securities gains $ 467 $ 77 $ 190 Income before taxes 467 77 190 Tax expense 120 20 50 Net income $ 347 $ 57 $ 140 Amortization of defined benefit pension plan items: Affected line item in the Consolidated Statements of Income: Recognized actuarial loss (1) $ (874) $ (1,059) $ (1,000) Income before taxes (874) (1,059) (1,000) Tax benefit (223) (277) (261) Net loss $ (651) $ (782) $ (739) (1) This amount is included in the computation of net periodic benefit cost, see Note 14.

DERIVATIVES

DERIVATIVES	12 Months Ended
	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVES	DERIVATIVESThe Company enters into interest rate swaps to facilitate customer transactions and meet their financing needs. These swaps qualify as derivatives, but are not designated as hedging instruments. Interest rate swap contracts involve the risk of dealing with counterparties and their ability to meet contractual terms. When the fair value of a derivative instrument contract is positive, this generally indicates that the counterparty or customer owes the Company, and results in credit risk to the Company. When the fair value of a derivative instrument contract is negative, the Company owes the customer or counterparty and therefore, has no credit risk. The swap positions are offset to minimize the potential impact on the Company’s financial statements. Credit risk exists if the borrower’s collateral or financial condition indicates that the underlying collateral or financial condition of the borrower makes it probable that amounts due will be uncollectible. Any amounts due to the Company will be expected to be collected from the borrower. Management reviews this credit exposure on a quarterly basis. At December 31, 2020 and 2019, all loans associated with the swap agreements were determined to be “pass” rated credits as provided by regulatory guidance and therefore no component of credit loss was factored into the valuation of the swaps. A summary of the Company’s interest rate swaps at December 31 for the years indicated is included in the following table: 2020 Notional Amount Estimated Fair Value Years to Maturity Receive Pay Interest rate swap agreements: Pay fixed/receive variable swaps $ 160,261 $ (9,183) 8.7 years 2.39 % 3.72 % Pay variable/receive fixed swaps 160,261 9,183 8.7 years 3.72 % 2.39 % Total swaps $ 320,522 $ — 8.7 years 3.06 % 3.06 % 2019 Notional Amount Estimated Fair Value Years to Maturity Receive Pay Interest rate swap agreements: Pay fixed/receive variable swaps $ 102,337 $ (2,507) 9.1 years 3.40 % 4.11 % Pay variable/receive fixed swaps 102,337 2,507 9.1 years 4.11 % 3.40 % Total swaps $ 204,674 $ — 9.1 years 3.76 % 3.76 % The estimated fair value of the swaps at December 31 for the periods indicated in the table above were recorded in other assets and other liabilities in the Consolidated Statements of Financial Condition. The associated net gains and losses on the swaps are recorded in other non-interest income in the Consolidated Statement of Income.

FINANCIAL INSTRUMENTS WITH OFF-

FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Disclosure [Abstract]
FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK	FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK In the normal course of business, the Company has various outstanding credit commitments that are not reflected in the financial statements. These commitments are made to satisfy the financing needs of the Company's clients. The associated credit risk is controlled by subjecting such activity to the same credit and quality controls as exist for the Company's lending and investing activities. The commitments involve diverse business and consumer customers and are generally well collateralized. Collateral held varies, but may include residential real estate, commercial real estate, property and equipment, inventory and accounts receivable. Commitments do not necessarily represent future cash requirements as a portion of the commitments have some reduced likelihood of being exercised. Additionally, many of the commitments are subject to annual reviews, material change clauses or requirements for inspections prior to draw funding that could result in a curtailment of the funding commitments. A summary of the financial instruments with off-balance sheet credit risk is as follows at December 31 for the years indicated: (In thousands) 2020 2019 Commercial real estate development and construction $ 871,290 $ 571,368 Residential real estate-development and construction 94,096 89,224 Real estate-residential mortgage 335,288 74,282 Lines of credit, principally home equity and business lines 1,947,706 1,400,038 Standby letters of credit 71,777 62,065 Total Commitments to extend credit and available credit lines $ 3,320,157 $ 2,196,977

LITIGATION

LITIGATION	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
LITIGATION	LITIGATIONThe Company and its subsidiaries are subject in the ordinary course of business to various pending or threatened legal proceedings in which claims for monetary damages are asserted. After consultation with legal counsel, management does not anticipate that the ultimate liability, if any, arising out of currently pending legal proceedings will have a material adverse effect on the Company’s financial condition, operating results or liquidity.

FAIR VALUE

FAIR VALUE	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
FAIR VALUE	FAIR VALUE GAAP provides entities the option to measure eligible financial assets, financial liabilities and commitments at fair value (i.e. the fair value option), on an instrument-by-instrument basis, that are otherwise not permitted to be accounted for at fair value under other accounting standards. The election to use the fair value option is available when an entity first recognizes a financial asset or financial liability or upon entering into a commitment. Subsequent changes in fair value must be recorded in earnings. The Company applies the fair value option on residential mortgage loans held for sale. The fair value option on residential mortgage loans allows the recognition of gains on sale of mortgage loans to more accurately reflect the timing and economics of the transaction. The standard for fair value measurement establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are described below. Basis of Fair Value Measurement: Level 1 - Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. Level 2 - Quoted prices in markets that are not active, or inputs that are observable, either directly or indirectly, for substantially the full term of the asset or liability. Level 3 - Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e. supported by little or no market activity). A financial instrument’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. Changes to interest rates may result in changes in the cash flows due to prepayments or extinguishments. Accordingly, this could result in higher or lower measurements of the fair values. Assets and Liabilities Residential mortgage loans held for sale Residential mortgage loans held for sale are valued based on quotations from the secondary market for similar instruments and are classified as Level 2 in the fair value hierarchy. Investments available-for-sale U.S. treasuries and government agencies securities and mortgage-backed and asset-backed securities Valuations are based on active market data and use of evaluated broker pricing models that vary based by asset class and includes available trade, bid, and other market information. Generally, the methodology includes broker quotes, proprietary models, descriptive terms, and databases coupled with extensive quality control programs. Quality control evaluation processes use available market, credit and deal level information to support the evaluation of the security. Additionally, proprietary models and pricing systems, mathematical tools, actual transacted prices, integration of market developments and experienced evaluators are used to determine the value of a security based on a hierarchy of market information regarding a security or securities with similar characteristics. The Company does not adjust the quoted price for such securities. Such instruments are classified within Level 2 in the fair value hierarchy. State and municipal securities The Company primarily uses prices obtained from third-party pricing services to determine the fair value of state and municipal securities. The Company independently evaluates and corroborates the fair value received from pricing services through various methods and techniques, including references to dealer or other market quotes, by reviewing valuations of comparable instruments, and by comparing the prices realized on the sale of similar securities. Such securities are classified within Level 2 in the fair value hierarchy. Corporate debt The fair value of corporate debt is determined by utilizing a discounted cash flow valuation technique employed by a third-party valuation specialist. The third-party specialist uses assumptions related to yield, prepayment speed, conditional default rates and loss severity based on certain factors such as, credit worthiness of the counterparty, prevailing market rates, and analysis of similar securities. The Company evaluates the fair values provided by the third-party specialist for reasonableness and classifies them as level 3 in the fair value hierarchy. Interest rate swap agreements Interest rate swap agreements are measured by alternative pricing sources using a discounted cash flow method that incorporates current market interest rates. Based on the complex nature of interest rate swap agreements, the markets these instruments trade in are not as efficient and are less liquid than that of the more mature Level 1 markets. These characteristics classify interest rate swap agreements as Level 2 in the fair value hierarchy. Assets and Liabilities Measured at Fair Value on a Recurring Basis The following tables set forth the Company’s financial assets and liabilities at the December 31 for the years indicated that were accounted for or disclosed at fair value. Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement: 2020 (In thousands) Quoted Prices in Significant Other Significant Total Assets Residential mortgage loans held for sale (1) $ — $ 78,294 $ — $ 78,294 Investments available-for-sale: U.S. government agencies — 43,297 — 43,297 State and municipal — 390,367 — 390,367 Mortgage-backed and asset-backed — 904,432 — 904,432 Corporate debt — — 9,925 9,925 Total available-for-sale securities — 1,338,096 9,925 1,348,021 Interest rate swap agreements — 9,183 — 9,183 Total assets $ — $ 1,425,573 $ 9,925 $ 1,435,498 Liabilities Interest rate swap agreements $ — $ (9,183) $ — $ (9,183) Total liabilities $ — $ (9,183) $ — $ (9,183) (1) The outstanding principal balance for residential loans held for sale as of December 31, 2020 was $75.5 million. 2019 (In thousands) Quoted Prices in Significant Other Significant Total Assets Residential mortgage loans held for sale (1) $ — $ 53,701 $ — $ 53,701 Investments available-for-sale: U.S. government agencies — 258,495 — 258,495 State and municipal — 233,649 — 233,649 Mortgage-backed and asset-backed — 570,759 — 570,759 Corporate debt — — 9,552 9,552 Trust preferred — — 310 310 Total debt securities — 1,062,903 9,862 1,072,765 Marketable equity securities — 568 — 568 Total available-for-sale securities — 1,063,471 9,862 1,073,333 Interest rate swap agreements — 2,507 — 2,507 Total assets $ — $ 1,119,679 $ 9,862 $ 1,129,541 Liabilities Interest rate swap agreements $ — $ (2,507) $ — $ (2,507) Total liabilities $ — $ (2,507) $ — $ (2,507) (1) The outstanding principal balance for residential loans held for sale as of December 31, 2019 was $52.6 million. The fair value of investments transferred or that are purchased and placed in Level 3 is estimated by discounting the expected future cash flows using the current rates for investments with similar credit ratings and similar remaining maturities. Expected cash flows were projected based on contractual cash flows. The following table provides activity of assets reported as Level 3 for the period indicated: Significant Unobservable Inputs (In thousands) (Level 3) Investments available-for-sale: Balance at January 1, 2020 $ 9,862 Transfer into Level 3 assets — Additions of Level 3 assets 3,050 Elimination of investments in WashingtonFirst and Revere sub debt (3,000) Sales of Level 3 assets (310) Total unrealized gains included in accumulated other comprehensive income 323 Balance at December 31, 2020 $ 9,925 Assets Measured at Fair Value on a Non-recurring Basis The following tables set forth the Company’s financial assets subject to fair value adjustments on a non-recurring basis at December 31 for the year indicated that are valued at the lower of cost or market. Assets are classified in their entirety based on the lowest level of input that is significant to the fair value measurement: 2020 (In thousands) Quoted Prices in Significant Other Significant Total Total Losses Loans (1) $ — $ — $ 13,901 $ 13,901 $ (11,326) Other real estate owned — — 1,455 1,455 (286) Total $ — $ — $ 15,356 $ 15,356 $ (11,612) (1) Amounts represent the fair value of collateral for collateral dependent non-accrual loans allocated to the allowance for credit losses. Fair values are determined using actual market prices (Level 2), independent third party valuations and borrower records, discounted as appropriate (Level 3). 2019 (In thousands) Quoted Prices in Significant Other Significant Total Total Losses Loans (1) $ — $ — $ 6,886 $ 6,886 $ (6,299) Other real estate owned — — 1,482 1,482 (281) Total $ — $ — $ 8,368 $ 8,368 $ (6,580) (1) Amounts represent the fair value of collateral for collateral dependent non-accrual loans allocated to the allowance for credit losses. Fair values are determined using actual market prices (Level 2), independent third party valuations and borrower records, discounted as appropriate (Level 3). At December 31, 2020, loans totaling $97.7 million were written down to fair value of $86.3 million as a result of individual credit loss allowances of $11.4 million associated with the collateral dependent non-accrual loans which was included in the allowance for credit losses. Loans totaling $24.8 million were written down to fair value of $19.3 million at December 31, 2019 as a result of individual credit loss allowances of $5.5 million associated with the collateral dependent non-accrual loans. Fair value of the collateral dependent loans is measured based on the loan’s observable market price or the fair value of the collateral (less estimated selling costs). Collateral may be real estate and/or business assets such as equipment, inventory and/or accounts receivable. The value of business equipment, inventory and accounts receivable collateral is based on net book value on the business’ financial statements and, if necessary, discounted based on management’s review and analysis. Appraised and reported values may be discounted based on management’s historical experience, changes in market conditions from the time of valuation, and/or management’s expertise and knowledge of the client and client’s business. Collateral dependent loans are reviewed and evaluated on at least a quarterly basis for additional individual reserve and adjusted accordingly, based on the factors identified above. OREO is adjusted to fair value upon transfer of the loans to OREO. Subsequently, OREO is carried at the lower of carrying value or fair value, less cost of disposal. The estimated fair value for OREO included in Level 3 is determined by independent market based appraisals and other available market information, less cost of disposal, that may be reduced further based on market expectations or an executed sales agreement. If the fair value of the collateral deteriorates subsequent to initial recognition, the Company records the OREO as a non-recurring Level 3 adjustment. Valuation techniques are consistent with those techniques applied in prior periods. Fair Value of Financial Instruments The Company discloses fair value information, based on the exit price notion, of financial instruments that are not measured at fair value in the financial statements. Fair value is the amount at which a financial instrument could be exchanged in a current transaction between willing parties, other than in a forced sale or liquidation, and is best evidenced by a quoted market price, if one exists. Quoted market prices, where available, are shown as estimates of fair market values. Because no quoted market prices are available for a significant portion of the Company's financial instruments, the fair value of such instruments has been derived based on the amount and timing of future cash flows and estimated discount rates based on observable inputs (“Level 2”) or unobservable inputs (“Level 3”). Present value techniques used in estimating the fair value of many of the Company's financial instruments are significantly affected by the assumptions used. In that regard, the derived fair value estimates cannot be substantiated by comparison to independent markets and, in many cases, could not be realized in immediate cash settlement of the instrument. Additionally, the accompanying estimates of fair values are only representative of the fair values of the individual financial assets and liabilities, and should not be considered an indication of the fair value of the Company. Management utilizes internal models used in asset liability management to determine the fair values disclosed below. The carrying amounts and fair values of the Company’s financial instruments at December 31 for the year indicated are presented in the following table: Fair Value Measurements 2020 Quoted Prices in Significant Other Significant (In thousands) Carrying Estimated Financial assets: Cash and cash equivalents $ 297,003 $ 297,003 $ 297,003 $ — $ — Residential mortgage loans held for sale 78,294 78,294 — 78,294 — Investments available-for-sale 1,348,021 1,348,021 — 1,338,096 9,925 Equity securities 65,760 65,760 65,760 — — Loans, net of allowance 10,235,142 10,336,355 — — 10,336,355 Interest rate swap agreements 9,183 9,183 — 9,183 — Accrued interest receivable 46,431 46,431 46,431 — — Bank owned life insurance 126,887 126,887 — 126,887 — Financial liabilities: Time deposits $ 1,657,662 $ 1,674,112 $ — $ 1,674,112 $ — Other deposits 8,375,407 8,375,407 8,375,407 — — Securities sold under retail repurchase agreements and federal funds purchased 543,157 543,157 — 543,157 — Advances from FHLB 379,075 390,593 — 390,593 — Subordinated debt 227,088 227,512 — — 227,512 Interest rate swap agreements 9,183 9,183 — 9,183 — Accrued interest payable 3,254 3,254 3,254 — — Fair Value Measurements 2019 Quoted Prices in Significant Other Significant (In thousands) Carrying Estimated Financial assets: Cash and cash equivalents $ 146,103 $ 146,103 $ 146,103 $ — $ — Residential mortgage loans held for sale 53,701 53,701 — 53,701 — Investments available-for-sale 1,073,333 1,073,333 — 1,063,471 9,862 Equity securities 51,803 51,803 51,803 — — Loans, net of allowance 6,649,100 6,628,054 — — 6,628,054 Interest rate swap agreements 2,507 2,507 — 2,507 — Accrued interest receivable 23,282 23,282 23,282 — — Bank owned life insurance 113,171 113,171 — 113,171 — Financial liabilities: Time deposits $ 1,542,322 $ 1,547,116 $ — $ 1,547,116 $ — Other deposits 4,897,997 4,897,997 4,897,997 — — Securities sold under retail repurchase agreements and federal funds purchased 213,605 213,605 — 213,605 — Advances from FHLB 513,777 520,729 — 520,729 — Subordinated debt 209,406 200,864 — — 200,864 Interest rate swap agreements 2,507 2,507 — 2,507 — Accrued interest payable 4,194 4,194 4,194 — —

PARENT COMPANY FINANCIAL INFORM

PARENT COMPANY FINANCIAL INFORMATION	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Disclosure [Abstract]
PARENT COMPANY FINANCIAL INFORMATION	PARENT COMPANY FINANCIAL INFORMATION Financial statements for Sandy Spring Bancorp, Inc. (Parent Only) for the periods indicated are presented in the following tables: Statements of Condition December 31, (In thousands) 2020 2019 Assets: Cash and cash equivalents $ 63,943 $ 90,361 Investments available-for-sale (at fair value) 9,925 10,430 Equity securities 568 — Investment in subsidiary 1,589,483 1,242,229 Goodwill 1,292 1,292 Other assets 2,684 1,480 Total assets $ 1,667,895 $ 1,345,792 Liabilities: Subordinated debt $ 196,454 $ 209,406 Accrued expenses and other liabilities 1,486 3,412 Total liabilities 197,940 212,818 Stockholders’ Equity: Common stock 47,057 34,970 Additional paid in capital 846,922 586,622 Retained earnings 557,271 515,714 Accumulated other comprehensive income/ (loss) 18,705 (4,332) Total stockholders’ equity 1,469,955 1,132,974 Total liabilities and stockholders’ equity $ 1,667,895 $ 1,345,792 Statements of Income Year Ended December 31, (In thousands) 2020 2019 2018 Income: Cash dividends from subsidiary $ 74,410 $ 42,625 $ 39,370 Other income 932 1,093 897 Total income 75,342 43,718 40,267 Expenses: Interest 9,028 3,141 1,922 Other expenses 1,505 1,507 1,135 Total expenses 10,533 4,648 3,057 Income before income taxes and equity in undistributed income of subsidiary 64,809 39,070 37,210 Income benefit (1,988) (734) (283) Income before equity in undistributed income of subsidiary 66,797 39,804 37,493 Equity in undistributed income of subsidiary 30,156 76,629 63,371 Net income $ 96,953 $ 116,433 $ 100,864 Statements of Cash Flows Year Ended December 31, (In thousands) 2020 2019 2018 Cash Flows from Operating Activities: Net income $ 96,953 $ 116,433 $ 100,864 Adjustments to reconcile net income to net cash provided by operating activities: Equity in undistributed income-subsidiary (30,156) (76,629) (63,371) Share based compensation expense 3,850 3,042 2,645 Tax benefit from stock options exercised 5 7 8 Other-net (9,732) — (3,252) Net cash provided by/ (used in) operating activities 60,920 42,853 36,894 Cash Flows from Investing Activities: Proceeds from sales of investment available-for-sale 310 — — Investment in subsidiary — (85,000) — Acquisition of business activity, net of cash paid — — 11,845 Net cash provided by/ (used in) investing activities 310 (85,000) 11,845 Cash Flows from Financing Activities: Retirement of subordinated debt (10,310) — — Proceeds from issuance of subordinated debt — 175,000 — Proceeds from issuance of common stock 1,997 1,433 1,395 Stock tendered for payment of withholding taxes (458) (703) (760) Repurchase of common stock (25,702) (24,284) — Dividends paid (53,175) (42,272) (39,277) Net cash provided by/ (used in) financing activities (87,648) 109,174 (38,642) Net increase/ (decrease) in cash and cash equivalents (26,418) 67,027 10,097 Cash and cash equivalents at beginning of year 90,361 23,334 13,237 Cash and cash equivalents at end of year $ 63,943 $ 90,361 $ 23,334

REGULATORY MATTERS

REGULATORY MATTERS	12 Months Ended
	Dec. 31, 2020
Banking and Thrift [Abstract]
REGULATORY MATTERS	REGULATORY MATTERS The Company and the Bank are subject to various regulatory capital requirements administered by the federal banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material effect on the Company's and the Bank's financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, the Bank must meet specific capital guidelines that involve quantitative measures of the Bank's assets, liabilities, and certain off-balance sheet items as calculated under regulatory accounting practices. The Company and the Bank's capital amounts and classifications are also subject to qualitative judgments by the regulators about components, risk weightings, and other factors. Quantitative measures established and defined by regulation to ensure capital adequacy require the Company and the Bank to maintain minimum amounts and ratios of Total, Tier 1 and Common Equity Tier 1 capital to risk-weighted assets, and of Tier 1 capital to average assets. As of December 31, 2020 and 2019, the capital levels of the Company and the Bank substantially exceeded all applicable capital adequacy requirements. As of December 31, 2020, the most recent notification from the Bank’s primary regulator categorized the Bank as well capitalized under the regulatory framework for prompt corrective action. To be categorized as well capitalized the Bank must maintain minimum Total risk-based, Tier 1 risk-based, Common Equity Tier 1 risk-based, and Tier 1 leverage ratios as set forth in the following table. There are no conditions or events since that notification that management believes have changed the Bank's category. The Company's and the Bank's actual capital amounts and ratios at December 31 for the years indicated are presented in the following table: Actual For Capital To be Well (Dollars in thousands) Amount Ratio Amount Ratio Amount Ratio As of December 31, 2020 Tier 1 Leverage: Company $ 1,078,213 8.92 % $ 483,619 4.00 % N/A N/A Sandy Spring Bank $ 1,199,570 9.93 % $ 483,175 4.00 % $ 603,969 5.00 % Common Equity Tier 1 Capital to risk- weighted assets: Company $ 1,078,213 10.58 % $ 458,612 4.50 % N/A N/A Sandy Spring Bank $ 1,199,570 11.79 % $ 457,920 4.50 % $ 661,441 6.50 % Tier 1 Capital to risk-weighted assets: Company $ 1,078,213 10.58 % $ 611,483 6.00 % N/A N/A Sandy Spring Bank $ 1,199,570 11.79 % $ 610,561 6.00 % $ 814,081 8.00 % Total Capital to risk-weighted assets: Company $ 1,419,973 13.93 % $ 815,311 8.00 % N/A N/A Sandy Spring Bank $ 1,347,102 13.24 % $ 814,081 8.00 % $ 1,017,601 10.00 % As of December 31, 2019 Tier 1 Leverage: Company $ 794,300 9.70 % $ 327,577 4.00 % N/A N/A Sandy Spring Bank $ 894,659 10.94 % $ 327,123 4.00 % $ 408,904 5.00 % Common Equity Tier 1 Capital to risk- weighted assets: Company $ 783,903 11.06 % $ 318,860 4.50 % N/A N/A Sandy Spring Bank $ 894,659 12.65 % $ 318,259 4.50 % $ 459,708 6.50 % Tier 1 Capital to risk-weighted assets: Company $ 794,300 11.21 % $ 425,147 6.00 % N/A N/A Sandy Spring Bank $ 894,659 12.65 % $ 424,346 6.00 % $ 565,794 8.00 % Total Capital to risk-weighted assets: Company $ 1,052,328 14.85 % $ 566,863 8.00 % N/A N/A Sandy Spring Bank $ 950,793 13.44 % $ 565,794 8.00 % $ 707,243 10.00 %

SEGMENT REPORTING

SEGMENT REPORTING	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
SEGMENT REPORTING	SEGMENT REPORTING Currently, the Company conducts business in three operating segments: Community Banking, Insurance and Investment Management. Each of the operating segments is a strategic business unit that offers different products and services. The Insurance and Investment Management segments were businesses that were acquired in separate transactions where management of the acquired business was retained. The accounting policies of the segments are the same as those of the Company. However, the segment data reflects inter-segment transactions and balances. The Community Banking segment is conducted through Sandy Spring Bank and involves delivering a broad range of financial products and services, including various loan and deposit products, to both individuals and businesses. Parent company income and assets are included in the Community Banking segment, as the majority of parent company functions are related to this segment. Beginning on April 1, 2020, the Community Banking segment includes the impact from the Revere acquisition. Major revenue sources include net interest income, gains on sales of mortgage loans, trust income fees and service charges on deposit accounts. Expenses include personnel, occupancy, marketing, equipment and other expenses. Non-cash charges associated with amortization of intangibles related to the acquired entities in the Community Banking segment totaled $4.3 million, $1.7 million and $1.9 million for the years ended December 31, 2020, December 31, 2019 and December 31, 2018, respectively. The Insurance segment is conducted through Sandy Spring Insurance, a subsidiary of the Bank. Sandy Spring Insurance operates Sandy Spring Insurance, a general insurance agency located in Annapolis, Maryland, and Neff and Associates, located in Ocean City, Maryland. Major sources of revenue are insurance commissions from commercial lines, personal lines, and medical liability lines. Expenses include personnel, occupancy, support charges and other expenses. Non-cash charges associated with amortization of intangibles related to the acquired entities were $0.1 million for each of the years ended December 31, 2020, 2019 and 2018. The Investment Management segment is conducted through West Financial and RPJ, subsidiaries of the Bank. These asset management and financial planning firms, located in McLean, Virginia and Falls Church, Virginia, respectively, provide comprehensive investment management and financial planning to individuals, families, small businesses and associations, including cash flow analysis, investment review, tax planning, retirement planning, insurance analysis and estate planning. West Financial and RPJ had approximately $3.4 billion in combined assets under management. Major revenue sources include non-interest income earned on the above services. Expenses include personnel, occupancy, support charges and other expenses. Non-cash charges associated with amortization of intangibles related to the acquired entities was $1.9 million for the year ended 2020 and was $0.1 million for each of the years ended 2019 and 2018. Information for the operating segments and reconciliation of the information to the consolidated financial statements for the years ended December 31 is presented in the following tables: 2020 Community Investment Inter-Segment Interest income $ 423,560 $ 6 $ 7 $ (13) $ 423,560 Interest expense 60,414 — — (13) 60,401 Provision for credit losses 85,669 — — — 85,669 Non-interest income 78,940 6,810 17,831 (865) 102,716 Non-interest expenses 237,910 5,686 13,051 (865) 255,782 Income before income taxes 118,507 1,130 4,787 — 124,424 Income tax expense 25,907 313 1,251 — 27,471 Net income $ 92,600 $ 817 $ 3,536 $ — $ 96,953 Assets $ 12,800,537 $ 11,335 $ 57,768 $ (71,211) $ 12,798,429 2019 (In thousands) Community Investment Inter-Segment Interest income $ 347,867 $ 26 $ 13 $ (37) $ 347,869 Interest expense 82,598 — — (37) 82,561 Provision for credit losses 4,684 — — — 4,684 Non-interest income 55,042 6,621 10,326 (667) 71,322 Non-interest expenses 166,802 5,731 7,219 (667) 179,085 Income before income taxes 148,825 916 3,120 — 152,861 Income tax expense 35,350 258 820 — 36,428 Net income $ 113,475 $ 658 $ 2,300 $ — $ 116,433 Assets $ 8,624,590 $ 10,340 $ 16,424 $ (22,352) $ 8,629,002 2018 Community Investment Inter-Segment Interest income $ 324,081 $ 3 $ 8 $ (10) $ 324,082 Interest expense 63,647 — — (10) 63,637 Provision for credit losses 9,023 — — — 9,023 Non-interest income 45,841 6,153 9,670 (615) 61,049 Non-interest expenses 168,261 5,601 6,536 (615) 179,783 Income before income taxes 128,991 555 3,142 — 132,688 Income tax expense 30,827 169 828 — 31,824 Net income $ 98,164 $ 386 $ 2,314 $ — $ 100,864 Assets $ 8,246,282 $ 9,165 $ 16,332 $ (28,507) $ 8,243,272

QUARTERLY FINANCIAL RESULTS (UN

QUARTERLY FINANCIAL RESULTS (UNAUDITED)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
QUARTERLY FINANCIAL RESULTS (UNAUDITED)	QUARTERLY FINANCIAL RESULTS (UNAUDITED) A summary of selected consolidated quarterly financial data for the years ended December 31 is provided in the following tables: 2020 (In thousands, except per share data) First Second Third Fourth Interest income $ 83,858 $ 114,927 $ 112,984 $ 111,791 Interest expense 19,524 13,413 15,500 11,964 Net interest income 64,334 101,514 97,484 99,827 Provision/ (credit) for credit losses 24,469 58,686 7,003 (4,489) Non-interest income 18,168 22,924 29,390 32,234 Non-interest expense 47,746 85,438 60,937 61,661 Income before income taxes 10,287 (19,686) 58,934 74,889 Income tax expense/ (benefit) 300 (5,348) 14,292 18,227 Net income/ (loss) $ 9,987 $ (14,338) $ 44,642 $ 56,662 Basic net income/ (loss) per common share $ 0.29 $ (0.31) $ 0.94 $ 1.19 Diluted net income/ (loss) per common share $ 0.28 $ (0.31) $ 0.94 $ 1.19 2019 (In thousands, except per share data) First Second Third Fourth Interest income $ 88,183 $ 87,214 $ 87,082 $ 85,390 Interest expense 21,433 21,029 20,292 19,807 Net interest income 66,750 66,185 66,790 65,583 Provision/ (credit) for loan losses (128) 1,633 1,524 1,655 Non-interest income 16,969 16,556 18,573 19,224 Non-interest expense 44,192 43,887 44,925 46,081 Income before income taxes 39,655 37,221 38,914 37,071 Income tax expense 9,338 8,945 9,531 8,614 Net income $ 30,317 $ 28,276 $ 29,383 $ 28,457 Basic net income per common share $ 0.85 $ 0.79 $ 0.82 $ 0.80 Diluted net income per common share $ 0.85 $ 0.79 $ 0.82 $ 0.80

SIGNIFICANT ACCOUNTING POLICI_2

SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations Sandy Spring Bancorp, Inc. ("Sandy Spring" or, together with its subsidiaries, the "Company"), a Maryland corporation, is the bank holding company for Sandy Spring Bank (the “Bank”), which conducts a full-service commercial banking, mortgage banking and trust business. Services to individuals and businesses include accepting deposits, extending credit to buy real estate or equipment, consumer and commercial loans and lines of credit, general insurance, personal trust, and investment and wealth management services. The Company operates in central Maryland, Northern Virginia, and the greater Washington D.C. market. The Company offers investment and wealth management services through the Bank’s subsidiaries, West Financial Services ("West Financial") and Rembert Pendleton Jackson ("RPJ"). Insurance products are available to clients through Sandy Spring Insurance Corporation ("Sandy Spring Insurance"), and Neff & Associates, which are agencies of Sandy Spring Insurance.
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 financial information. 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. The Company has evaluated subsequent events through the date of the issuance of its financial statements.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiary, Sandy Spring Bank and its subsidiaries, Sandy Spring Insurance, West Financial and RPJ. Consolidation has resulted in the elimination of all significant intercompany accounts and transactions. See Note 25 for more information on the Company's segments and consolidation.
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, in addition to affecting 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 credit losses and the related allowance, potential impairment of goodwill or other intangible assets, valuation of investment securities and the determination of whether available-for-sale debt securities with fair values less than amortized costs are impaired and require an allowance for credit losses, valuation of other real estate owned ("OREO"), 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.
Assets Under Management	Assets Under Management Assets held for others under fiduciary and agency relationships are not assets of the Company or its subsidiaries and are not included in the accompanying Consolidated Statements of Condition. Trust department income and investment management fees are presented on an accrual basis.
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 an original maturity of three months or less).
Revenue from Contract with Customers	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 Consolidated Statements of Income. Most of the Company’s revenue is not within the scope of Accounting Standard Codification (“ASC”) 606 – Revenue from Contracts with Customers. For revenue within the scope of ASC 606, 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 revenue recognition guidance. Wealth Management Income West Financial and RPJ provide 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 Sandy Spring Insurance is a producer. Sandy Spring Insurance 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. An 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 is recognized at month end. The overdraft services obligation is satisfied at the time of the overdraft and revenue is recognized as earned.
Residential Mortgage Loans Held For Sale	Residential Mortgage Loans Held for Sale The Company engages in sales of residential mortgage loans originated by the Bank. Loans held for sale are carried at fair value. Fair value is derived from secondary market quotations for similar instruments. The Company measures residential mortgage loans at fair value when the Company first recognizes the loan (i.e., the fair value option), as permitted by current accounting standards. Changes in fair value of these loans are recorded in earnings as a component of mortgage banking activities in non-interest income in the Consolidated Statements of Income. The Company's current practice is to sell the majority of such loans on a servicing released basis. Any retained servicing assets are amortized in proportion to their net servicing fee income over the life of the respective loans. Servicing assets are evaluated for impairment on a periodic basis.
Investments Available-for-sale	Investments Available-for-Sale Debt securities not classified as held to maturity or trading are classified as securities available-for-sale. Securities available-for-sale are acquired as part of the Company's asset/liability management strategy and may be sold in response to changes in interest rates, loan demand, changes in prepayment risk or other factors. Securities available-for-sale are carried at fair value, with unrealized gains or losses based on the difference between amortized cost and fair value, reported net of deferred tax, as accumulated other comprehensive income/ (loss), a separate component of stockholders' equity. The carrying values of securities available-for-sale are adjusted for premium amortization and discount accretion. Premium is amortized to the earliest call date and discount accreted to the maturity date using the effective interest method. Realized gains and losses on security sales or maturities, using the specific identification method, are included as a separate component of non-interest income. Related interest and dividends are included in interest income. Declines in the fair value of individual available-for-sale securities below their amortized cost due to credit-related factors are recognized as an allowance for credit losses. Credit-related factors affecting the determination of whether impairment has occurred include a downgrading of the security below investment grade by a rating agency or due to potential default, a significant deterioration in the financial condition of the issuer, increase in entity-specific credit spreads. Additionally, on any available-for-sale securities with unrealized losses, the Company evaluates its intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in fair value.
Equity Securities	Equity Securities Equity securities include Federal Reserve Bank stock, Federal Home Loan Bank of Atlanta ("FHLB") stock and other equities that are considered restricted as to marketability and recorded at cost. As these securities do not have readily available market values, they are carried at cost and adjusted for any necessary impairments each reporting period.
Loan Financing Receivables	Loan Financing Receivables The Company’s financing receivables consist primarily of loans that are stated at their principal balance outstanding, net of any unearned income, acquisition fair value marks and deferred loan origination fees and costs. Interest income on loans is accrued at the contractual rate based on the principal balance outstanding. Loan origination fees, net of certain direct origination costs, are deferred and recognized as an adjustment of the related loan yield using the interest method. The Company has provided short-term deferrals of loan principal and/or interest payments up to 180 days for customers who are affected by the COVID-19 pandemic. Customers receiving payment deferrals must meet certain criteria, such as being in good standing and not more than 30 days past due prior to the pandemic. In most cases, the deferred principal and/or interest amounts will be collected at the end of the life of the loan and will not accrue additional interest. The granting of a deferral of principal and/or interest under the Coronavirus Aid, Relief, and Economic Security (“CARES”) Act, which was enacted on March 27, 2020, and based on interagency guidelines, does not subject the loan to the past due, non-accrual, or troubled debt restructurings (“TDR”) policies described below. Upon exiting the loan modification deferral program, the measurement of loan delinquency will resume where it was determined upon entry into the program. The following discussions of past due, non-accrual and TDR policies remain valid for situations not covered by the CARES Act. Loans are considered past due or delinquent when the principal or interest due in accordance with the contractual terms of the loan agreement or any portion thereof remains unpaid after the due date of the scheduled payment. Immaterial shortfalls in payment amounts do not necessarily result in a loan being considered delinquent or past due. If any payments are past due and subsequent payments are resumed without payment of the delinquent amount, the loan shall continue to be considered past due. Whenever any loan is reported delinquent on a principal or interest payment or portion thereof, the amount reported as delinquent is the outstanding principal balance of the loan. Loans, except for consumer installment loans, are placed into non-accrual status when any portion of the loan principal or interest becomes 90 days past due. Management may determine that certain circumstances warrant earlier discontinuance of interest accruals on specific loans if an evaluation of other relevant factors (such as bankruptcy, interruption of cash flows, etc.) indicates collection of amounts contractually due is unlikely. These loans are considered, collectively, to be non-performing loans. Consumer installment loans that are not secured by real estate are not placed on non-accrual, but are charged down to their net realizable value when they are four months past due. Loans designated as non-accrual have all previously accrued but unpaid interest reversed from interest income. Interest income is not recognized on non-accrual loans. All payments received on non-accrual loans are applied using a cost-recovery method to reduce the outstanding principal balance until the loan returns to accrual status. Loans may be returned to accrual status when all principal and interest amounts contractually due are brought current and future payments are reasonably assured. Loans considered to be TDRs are loans that have their terms restructured (e.g., interest rates, loan maturity date, payment and amortization period, etc.) in circumstances that provide payment relief to a borrower experiencing financial difficulty. All restructured collateral-dependent loans are individually assessed for allowance for credit losses and may either be in accruing or non-accruing status. Non-accruing restructured loans may return to accruing status provided doubt has been removed concerning the collectability of principal and interest as evidenced by a sufficient period of payment performance in accordance with the restructured terms. Loans may be removed from the restructured category if the borrower is no longer experiencing financial difficulty, a re-underwriting event took place, and the revised loan terms of the subsequent restructuring agreement are considered to be consistent with terms that can be obtained in the market for loans with comparable credit risk. Allowance for Loan Losses (in accordance with ASC 450 and ASC 310) The allowance for loan losses (“allowance” or “ALL”) is an accounting standard applicable for periods ending December 31, 2019 and earlier and was replaced by the allowance for credit losses standard discussed below. The allowance under this standard represents an amount which, in management's judgment, is appropriate to absorb the probable estimate of losses that may be sustained on outstanding loans at the balance sheet date based on the evaluation of the size and current risk characteristics of the loan portfolio. The allowance is reduced by charge-offs, net of recoveries of previous losses, and is increased or decreased by a provision or credit for loan losses, which is recorded as a current period operating expense. The allowance is based on the basic principle that a loss be accrued when it is probable that the loss has occurred and the amount of the loss can be reasonably estimated. The Company’s methodology for estimating the allowance includes a general component reflecting historical losses, as adjusted, by loan portfolio segment, and a specific component for impaired loans. The general component is based upon historical loss experience by each portfolio segment measured, over the prior eight quarters weighted equally. The historical loss experience is supplemented to address various risk characteristics of the Company’s loan portfolio including: • trends in delinquencies and other non-performing loans; • changes in the risk profile related to large loans in the portfolio; • changes in the categories of loans comprising the loan portfolio; • concentrations of loans to specific industry segments; • changes in economic conditions on both a local and national level; • changes in the Company’s credit administration and loan portfolio management processes; and • the quality of the Company’s credit risk identification processes. The general component is calculated in two parts based on an internal risk classification of loans within each portfolio segment. Reserves on loans considered to be “classified” under regulatory guidance are calculated separately from loans considered to be “pass” rated under the same guidance. This segregation allows the Company to monitor the allowance component applicable to higher risk loans separate from the remainder of the portfolio in order to better manage risk and reasonably determine the sufficiency of reserves. Integral to the assessment of the allowance process is an evaluation that is performed to determine whether a specific allowance on an impaired credit is warranted. For the particular loan that may have potential impairment, an appraisal will be ordered depending on the time elapsed since the prior appraisal, the loan balance and/or the result of the internal evaluation. The Company typically relies on current (12 months old or less) third party appraisals of the collateral to assist in measuring impairment. In the cases in which the Company does not rely on a third party appraisal, an internal evaluation is prepared by an approved credit officer. A current appraisal on large loans is usually obtained if the appraisal on file is more than 12 months old and there has been a material change in market conditions, zoning, physical use or the appropriateness of the collateral based on an internal evaluation. The Company’s policy is to strictly adhere to regulatory appraisal standards. If an appraisal is ordered, no more than a 30 day turnaround is requested from the appraiser, who is selected by Credit Administration from an approved appraiser list. After receipt of the updated appraisal, the assigned credit officer will recommend to the Chief Credit Officer whether a specific allowance or a charge-off should be taken. When losses are confirmed, a charge-off is taken that is at least in the amount of the collateral deficiency as determined by the independent third party appraisal. Any further collateral deterioration results in either further specific reserves being established or additional charge-offs. The Chief Credit Officer has the authority to approve a specific allowance or charge-off between monthly credit committee meetings to ensure that there are no significant time lapses during this process. The portion of the allowance representing specific allowances is established on individually impaired loans. As a practical expedient, for collateral dependent loans, the Company measures impairment based on the net realizable value of the underlying collateral. For loans on which the Company has not elected to use a practical expedient to measure impairment, the Company will measure impairment based on the present value of expected future cash flows discounted at the loan’s effective interest rate. In determining the cash flows to be included in the discount calculation the Company considers the following factors that combine to estimate the probability and severity of potential losses: • the borrower’s overall financial condition; • resources and payment record; • demonstrated or documented support available from financial guarantors; and • the appropriateness of collateral value and the ultimate realization of that value at liquidation.
Allowance for Credit Losses	Allowance for Credit Losses (in accordance with ASC 326) The allowance for credit losses (“allowance” or “ACL”) represents an amount which, in management's judgment, represents the lifetime expected credit losses that may be sustained on outstanding loans at the statement of condition date based on the evaluation of the size and current risk characteristics of the loan portfolio, past events, current conditions, reasonable and supportable forecasts of future economic conditions and prepayment experience. The allowance is measured and recorded upon the initial recognition of a financial asset. The allowance is reduced by charge-offs, net of recoveries of previous losses, and is increased or decreased by a provision for credit losses, which is recorded as a current period expense. Determination of the appropriateness of the allowance is inherently complex and requires the use of significant and highly subjective estimates. The reasonableness of the allowance is reviewed periodically by the Risk Committee of the board of directors and formally approved quarterly by that same committee of the board. The Company’s methodology for estimating the allowance includes: (1) a collective quantified reserve that reflects the Company’s historical default and loss experience adjusted for expected economic conditions throughout a reasonable and supportable period and the Company’s prepayment and curtailment rates; (2) collective qualitative factors that consider concentrations of the loan portfolio, expected changes to the economic forecasts, large relationships, early delinquencies, and factors related to credit administrations, including, among others, loan-to-value ratios, borrowers’ risk rating and credit score migrations; and (3) individual allowances on collateral-dependent loans where borrowers are experiencing financial difficulty or when the Company determines that foreclosure is probable. The Company excludes accrued interest from the measurement of the allowance as the Company has a non-accrual policy to reverse any accrued, uncollected interest income as loans are moved to non-accrual status. Loans are pooled into segments based on the similar risk characteristics of the underlying borrowers, in addition to consideration of collateral type, industry and business purpose of the loans. Portfolio segments used to estimate the allowance are the same as portfolio segments used for general credit risk management purposes. Refer to Note 5 for more details on the Company’s portfolio segments. The Company applies two calculation methodologies to estimate the collective quantified component of the allowance: discounted cash flows method and weighted average remaining life method. Allowance estimates on commercial acquisition, development and construction (“AD&C”) and residential construction segments are based on the weighted average remaining life method. Allowance estimates on all other portfolio segments are based on the discounted cash flows method. Segments utilizing the discounted cash flows method are further sub-segmented into risk level pools, determined either by risk rating for commercial loans or Beacon Scores ranges for residential and consumer loans. To better manage risk and reasonably determine the sufficiency of reserves, this segregation allows the Company to monitor the allowance component applicable to higher risk loans separate from the remainder of the portfolio. Collective calculation methodologies utilize the Company’s historical default and loss experience adjusted for economic forecasts. The reasonable and supportable forecast period represents a two-year economic outlook for the applicable economic variables. Following the end of the reasonable and supportable forecast period expected losses revert back to the historical mean over the next two years on a straight-line basis. Economic variables that have the most significant impact on the allowance include: unemployment rate, house price index and number of business bankruptcies. Contractual loan level cash flows within the discounted cash flows methodology are adjusted for the Company’s historical prepayment and curtailment rate experience. The individual reserve assessment is applied to collateral dependent loans where borrowers are experiencing financial difficulty or when the Company determines that a foreclosure is probable. The determination of the fair value of the collateral depends on whether a repayment of the loan is expected to be from the sale or the operation of the collateral. When a repayment is expected from the operation of the collateral, the Company uses the present value of expected cash flows from the operation of the collateral as the fair value. When the repayment of the loan is expected from the sale of the collateral the fair value of the collateral is based on an observable market price or the collateral’s appraised value, less estimated costs to sell. Third-party appraisals used in the individual reserve assessment are conducted at least annually, or more frequently if deemed necessary, with underlying assumptions that are reviewed by management. Internal evaluations of collateral value are conducted quarterly to ensure any further deterioration of the collateral value is recognized on a timely basis. During the individual reserve assessment, management also considers the potential future changes in the value of the collateral over the remainder of the loan’s remaining life. The Company may receive updated appraisals which contradict the preliminary determination of fair value used to establish an individual allowance on a loan. In these instances the individual allowance is adjusted to reflect the Company’s evaluation of the updated appraised fair value. In the event a loss was previously confirmed and the loan was charged down to the estimated fair value based on a previous appraisal, the balance of partially charged-off loans are not subsequently increased, but could be further decreased depending on the direction of the change in fair value. Payments on fully or partially charged-off loans are accounted for under the cost-recovery method. Under this method, all payments received are applied on a cash basis to reduce the entire outstanding principal balance, then to recognize a recovery of all previously charged-off amounts before any interest income may be recognized. Based on the individual reserve assessment, if the Company determines that the fair value of the collateral is less than the amortized cost basis of the loan, an individual allowance will be established measured as the difference between the fair value of the collateral (less costs to sell) and the amortized cost basis of the loan. Once a loss has been confirmed, the loan is charged down to its estimated fair value. Large groups of smaller non-accrual homogeneous loans, including residential permanent and construction mortgages and consumer installment loans, are not individually evaluated for allowance. These portfolios are reserved for on a collective basis using historical loss rates of similar loans over the weighted average life of each pool. The Company reviews its unfunded commitments to determine if they are unconditionally cancellable by the Company. If the unfunded commitment is determined to not be unconditionally cancellable by the Company, a reserve for unfunded commitments is established. An estimate of the reserve for unfunded commitments considers both the likelihood that the funding will occur and an estimate of expected credit losses over the life of the commitment. Management believes it uses relevant information available to make determinations about the allowance and that it has established the existing allowance in accordance with GAAP. However, the determination of the allowance requires significant judgment, and estimates of expected lifetime losses in the loan portfolio can vary significantly from the amounts actually observed. While management uses available information to recognize expected losses, future additions to the allowance may be necessary based on changes in the loans comprising the portfolio, changes in the current and forecasted economic conditions, changes to the interest rate environment which may directly impact prepayment and curtailment rate assumptions, and changes in the financial condition of borrowers. Loans Acquired with Deteriorated Credit Quality (in accordance with ASC 310-30) Acquired loans with evidence of credit deterioration since their origination, commonly referred to as purchased credit impaired ("PCI") loans, are recorded at their initial fair values as of the date of the acquisition. The accounting standard for PCI loans was applicable for periods ending December 31, 2019 and earlier and was replaced with the accounting standard for purchase credit deteriorated loans as discussed below. 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 (non-accretable 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.
Acquired Loans	Acquired Loans (in accordance with ASC 326) Loans acquired in connection with acquisitions are recorded at their acquisition-date fair value. The allowance for credit losses related to the acquired loan portfolio is not carried over. Acquired loans are classified into two categories based on the credit risk characteristics of the underlying borrowers as either purchased credit deteriorated (“PCD”) loans, or loans with no evidence of credit deterioration (“non-PCD”). PCD loans are defined as a loan or pool of loans that have experienced more-than-insignificant credit deterioration since the origination date. The Company uses a combination of individual and pooled review approaches to determine if acquired loans are PCD. At acquisition, the Company considers a number of factors to determine if an acquired loan or pool of loans has experienced more-than-insignificant credit deterioration. These factors include: • loans classified as non-accrual, • loans with risk rating of special mention or worse (using the Company's risk rating scale), • loans with multiple risk rating downgrades since origination, • loans with evidence of being 60 days or more past due, • loans previously modified in a troubled debt restructuring, • loans that received an interest only or payment deferral modification, and • loans in industries that show evidence of additional risk due to economic conditions. The initial allowance related to PCD loans that share similar risk characteristics is established using a pooled approach. The Company uses either a discounted cash flow or weighted average remaining life method to determine the required level of the allowance. PCD loans that were classified as non-accrual as of the acquisition date and are collateral dependent are assessed for allowance on an individual basis. For PCD loans, an initial allowance is established on the acquisition date and added to the fair value of the loan to arrive at acquisition date amortized cost. Accordingly, no provision for credit losses is recognized on PCD loans at the acquisition date. Subsequent to the acquisition date, the initial allowance on PCD loans will increase or decrease based on future evaluations, with changes recognized in the provision for credit losses. Non-PCD loans are pooled into segments together with originated loans that share similar risk characteristics and have an allowance established on the acquisition date, which is recognized in the current period provision for credit losses. Determining the fair value of the acquired loans involves estimating the principal and interest payment cash flows expected to be collected on the loans and discounting those cash flows at a market rate of interest. Management considers a number of factors in evaluating the acquisition date fair value including the remaining life, interest rate profile, market interest rate environment, payment schedules, risk ratings, probability of default and loss given default, and estimated prepayment rates. For PCD loans, the non-credit discount or premium is allocated to individual loans as determined by the difference between the loan’s unpaid principal balance and amortized cost basis. The non-credit premium or discount is recognized into interest income on a level yield basis over the remaining expected life of the loan. For non-PCD loans, the fair value discount or premium is allocated to individual loans and recognized into interest income on a level yield basis over the remaining expected life of the loan.
Premises and Equipment	Premises and Equipment Premises and equipment are stated at cost, less accumulated depreciation and amortization, computed using the straight-line method. Premises and equipment are depreciated over the useful lives of the assets, which generally range from 3 to 10 years for furniture, fixtures and equipment, 3 to 5 years for computer software and hardware, and 10 to 40 years for buildings and building improvements. Leasehold improvements are amortized over the lesser of the lease term or the estimated useful lives of the improvements. The costs of major renewals and betterments are capitalized, while the costs of ordinary maintenance and repairs are included in non-interest expense.
Leases	Leases The Company determines if an arrangement is a lease at the contract's inception. All of the Company’s leases are currently classified as operating leases and the related right-of-use ("ROU") asset and lease liability are included in other assets and other liabilities, respectively, in the Company’s Consolidated Statements of Condition. ROU assets represent the Company’s right to use an underlying asset for the lease term, and lease liabilities represent the Company’s obligation to make lease payments arising from the lease arrangements. Operating lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of the expected future lease payments over the remaining lease term. In determining the present value of future lease payments, the Company uses its incremental borrowing rate based on the information available at the lease commencement date. The operating ROU assets are adjusted for any lease payments made at or before the lease commencement date, initial direct costs, any lease incentives received and, for acquired leases, any favorable or unfavorable fair value adjustments. The present value of the lease liability may include the impact of options to extend or terminate the lease when it is reasonably certain that the Company will exercise such options provided in the lease terms. Lease expense is recognized on a straight-line basis over the expected lease term. Lease agreements that include lease and non-lease components, such as common area maintenance charges, are accounted for separately.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill represents the excess purchase price paid over the fair value of the net assets acquired in a business combination. Goodwill is not amortized but is tested for impairment annually or more frequently if events or changes in circumstances indicate that the asset might be impaired. Impairment testing requires that the fair value of each of the Company’s reporting units be compared to the carrying amount of the reporting unit’s net assets, including goodwill. The Company’s reporting units were identified based upon an analysis of each of its individual operating segments. If the fair values of the reporting units exceed their book values, no write-down of recorded goodwill is required. If the fair value of a reporting unit is less than book value, an expense may be required to write-down the related goodwill to the proper carrying value. Any impairment would be realized through a reduction of goodwill or the intangible and an offsetting charge to non-interest expense. The Company performs an annual impairment test of goodwill as of September 30 of each year, and again at any quarter-end if any triggering events occur during a quarter that may affect goodwill. Examples of such events include, but are not limited to, adverse action by a regulator or a loss of key personnel. Determining the fair value of a reporting unit requires the Company to use a degree of subjectivity. The Company concluded that its annual impairment test of goodwill, and other intangible assets, did not result in an impairment. Additionally, the Company determined that there were no triggering events and as a result no evidence of impairment between the annual impairment test and December 31, 2020. Current accounting guidance provides the option to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. The Company assesses qualitative factors on a quarterly basis. Based on the assessment of these qualitative factors, if it is determined that it is more likely than not that the fair value of a reporting unit is not less than the carrying value, then performing the impairment process is not necessary. However, if it is determined that it is more likely than not that the carrying value exceeds the fair value a quantified analysis is required to determine whether an impairment exists. Other intangible assets represent purchased assets that lack physical substance but can be distinguished from goodwill because of contractual or other legal rights or because the asset is capable of being sold or exchanged either on its own or in combination with a related contract, asset, or liability. Other intangible assets have finite lives and are reviewed for impairment annually. These assets are amortized over their estimated useful lives either on a straight-line or sum-of-the-years basis over varying periods that initially did not exceed 15 years.
Other Real Estate Owned ("OREO")	Other Real Estate Owned OREO is comprised of properties acquired in partial or total satisfaction of problem loans. The properties are recorded at fair value less estimated costs of disposal, on the date acquired or on the date that the Company acquires effective control over the property. Gains or losses arising at the time of acquisition of such properties are charged against the allowance for credit losses. During the holding period OREO continues to be measured at lower of cost or fair value less estimated costs of disposal, and any subsequent declines in value are expensed as incurred. Gains and losses realized from the sale of OREO, as well as valuation adjustments and expenses of operation are included in non-interest expense.
Derivative Financial Instruments	Derivative Financial Instruments Derivative Loan Commitments Mortgage loan commitments are derivative loan commitments if the loan that will result from exercise of the commitment will be held for sale upon funding. Derivative loan commitments are recognized at fair value in the Consolidated Statements of Condition in other assets or other liabilities with changes in their fair values recorded as a component of mortgage banking activities in the Consolidated Statements of Income. Mortgage loan commitments are issued to borrowers. Subsequent to commitment date, changes in the fair value of the loan commitment are recognized based on changes in the fair value of the underlying mortgage loan due to interest rate changes, changes in the probability the derivative loan commitment will be exercised, and the passage of time. In estimating fair value, a probability is assigned to a loan commitment based on an expectation that it will be exercised and the loan will be funded. Forward Loan Sale Commitments Loan sales agreements are evaluated to determine whether they meet the definition of a derivative as facts and circumstances may differ significantly. If agreements qualify, to protect against the price risk inherent in derivative loan commitments, the Company utilizes both “mandatory delivery” and “best efforts” forward loan sale commitments to mitigate the risk of potential decreases in the values of loans that would result from the exercise of the derivative loan commitments. Mandatory delivery contracts are accounted for as derivative instruments. Generally, best efforts contracts also meet the definition of derivative instruments after the loan to the borrower has closed. Accordingly, forward loan sale commitments that economically hedge the closed loan inventory are recognized at fair value in the Consolidated Statements of Condition in other assets or other liabilities with changes in their fair values recorded as a component of mortgage banking activities in the Consolidated Statements of Income. The Company estimates the fair value of its forward loan sales commitments using a methodology similar to that used for derivative loan commitments. Interest Rate Swap Agreements The Company enters into interest rate swaps (“swaps”) with commercial loan customers to provide a facility to mitigate the fluctuations in the variable rate on the respective loans. These swaps are matched in exact offsetting terms to swaps that the Company enters into with an outside third party. The swaps are reported at fair value in other assets or other liabilities in the Consolidated Statements of Condition. The Company's swaps qualify as derivatives, but are not designated as hedging instruments, thus any net gain or loss resulting from changes in the fair value is recognized in other non-interest income in the Consolidated Statements of Income. Further discussion of the Company's financial derivatives is set forth in Note 19.
Off-Balance-Sheet Credit Risk	Off-Balance Sheet Credit Risk The Company issues financial or standby letters of credit that represent conditional commitments to fund transactions by the Company, typically to guarantee performance of a customer to a third-party related to borrowing arrangements. The credit risk associated with issuing letters of credit is essentially the same as occurs when extending loan facilities to borrowers. The Company monitors the exposure to the letters of credit as part of its credit review process. Extensions of letters of credit, if any, would become part of the loan balance outstanding and would be evaluated in accordance with the Company’s credit policies. Potential exposure to loss for unfunded letters of credit if deemed necessary would be recorded in other liabilities in the Consolidated Statements of Condition. In the ordinary course of business the Company originates and sells whole loans to a variety of investors. Mortgage loans sold are subject to representations and warranties made to the third-party purchasers regarding certain attributes. Subsequent to the sale, if a material underwriting deficiency or documentation defect is determined, the Company may be obligated to repurchase the mortgage loan or reimburse the investor for losses incurred if the deficiency or defect cannot be rectified within a specific period subsequent to discovery. The Company monitors the activity regarding the requirement to repurchase loans and the associated losses incurred. This information is applied to determine an estimated recourse reserve that is recorded in other liabilities in the Consolidated Statements of Condition.
Valuation of Long-Lived Assets	Valuation of Long-Lived Assets The Company reviews long-lived assets, including leases, and certain identifiable intangible assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparing the carrying amount of the asset to future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the estimated fair value of the assets. Assets to be disposed of are reported at the lower of the cost or the fair value, less costs to sell.
Transfers of Financial Assets	Transfers of Financial Assets Transfers of financial assets are accounted for as sales when control over the assets has been surrendered. Control over transferred assets is deemed to be surrendered when (1) the assets have been isolated from the Company, (2) the transferee obtains the right (free of conditions that constrain it from taking advantage of that right or from providing more than a trivial benefit to the transferor) to pledge or exchange the transferred assets, and (3) the Company does not maintain effective control over the transferred assets through any agreement to repurchase or redeem them before their maturity or likely cause a holder to return those assets whether through unilateral ability or a price so favorable to the transferee that it is probable that the transferee will require the transferor to repurchase them. A participating interest must be in an entire financial asset and cannot represent an interest in a group of financial assets. Except for compensation paid for services performed, all cash flows from the asset are allocated to the participating interest holders in proportion to their share of ownership. Financial assets obtained or liabilities incurred in a sale are recognized and initially measured at fair value.
Advertising Costs	Advertising Costs Advertising costs are expensed as incurred and included as marketing expense in non-interest expenses in the Consolidated Statements of Income.
Net Income per Common Share	Net Income per Common Share The Company calculates earnings per common share under the two class method, which provides that unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are participating securities and shall be included in the computation of earnings per share pursuant to the dual class method. The Company has determined that its outstanding non-vested restricted stock awards are participating securities. Under the dual class method, basic earnings per common share is computed by dividing net earnings allocated to common shareholders by the weighted average number of common shares outstanding during the applicable period, which excludes outstanding participating securities. Diluted earnings per common share is computed using the weighted average number of common shares determined for the basic earnings per common share computation plus the dilutive effect of incremental stock options and restricted stock.
Income Taxes	Income Taxes Income tax expense is based on the results of operations, adjusted for permanent differences between items of income or expense reported in the financial statements and those reported for tax purposes. Deferred income tax assets and liabilities are determined using the liability method. Under the liability method, deferred income taxes are determined based on the differences between the financial statement carrying amounts and the income tax bases of assets and liabilities and are measured at the enacted tax rates that will be in effect when these differences reverse. The effects of the enactment of the new tax law are accounted for under the existing authoritative guidance.
Adopted Accounting Pronouncements	Adopted Accounting Pronouncements The Financial Accounting Standards Board ("FASB") issued ASU 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 previous GAAP, entities generally amortized 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 was 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 Company adopted this standard during the current year and there was not a material impact on the Company’s financial position, results of operations or cash flows. The FASB issued ASU 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 was 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 Company adopted this standard during the current year and it did not have a material impact on the Company’s financial position, results of operations or cash flows. The FASB issued ASU No. 2016-13, Current Expected Credit Losses , in June 2016. This guidance changes the impairment model for most financial assets measured at amortized cost and certain other instruments. Entities who have adopted are now required to use an expected loss model, replacing the incurred loss model that was previously 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 conditions 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 will also be required to provide more disclosures, including information used to track credit quality by year of origination for most financing receivables. This guidance was effective for public business entities for the first interim or annual period beginning after December 15, 2019. The Company completed implementation of the guidance and adopted it in the first quarter of 2020. As a part of the implementation, the Company reconciled historical loan data, determined segmentation of the loan portfolio for application of the CECL calculation, determined the key assumptions, selected calculation methods, and established an internal controls framework. The Company also used the services of an independent third party advisor to validate the conceptual soundness of the methodology framework and of the CECL model. At the adoption date, exclusive of the reclassification of $2.8 million to the allowance for credit losses of amounts related to the previously acquired impaired loans, the after tax impact to retained earnings at the adoption date was $2.2 million based on the expected performance of the economy at the adoption date. Pending Accounting Pronouncements In March 2020, FASB released ASU 2020-04 - Reference Rate Reform (Topic 848) , which provides optional guidance to ease the accounting burden in accounting for, or recognizing the effects from, reference rate reform on financial reporting. The new standard is a result of the London Interbank Offered Rate ("LIBOR") likely being discontinued as an available benchmark rate. The standard is elective and provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships, or other transactions that reference LIBOR, or another reference rate expected to be discontinued. The amendments in the update are effective for all entities between March 12, 2020 and December 31, 2022. The Company has established a cross-functional working group to guide the Company’s transition from LIBOR and has begun efforts to transition to alternative rates consistent with industry timelines. The Company has identified its products that utilize LIBOR and has implemented enhanced fallback language to facilitate the transition to alternative reference rates. The Company is evaluating existing platforms and systems and preparing to offer new rates. In December 2019, FASB released ASU 2019-12 - Income Taxes (Topic 740) , which simplifies the accounting for income taxes by removing multiple exceptions to the general principals in Topic 740. The standard is effective for public business entities for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2020. The Company does not expect the adoption of this standard to have a material impact on the Company’s Consolidated Financial Statements.
Pending Accounting Pronouncements	Pending Accounting Pronouncements In March 2020, FASB released ASU 2020-04 - Reference Rate Reform (Topic 848) , which provides optional guidance to ease the accounting burden in accounting for, or recognizing the effects from, reference rate reform on financial reporting. The new standard is a result of the London Interbank Offered Rate ("LIBOR") likely being discontinued as an available benchmark rate. The standard is elective and provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships, or other transactions that reference LIBOR, or another reference rate expected to be discontinued. The amendments in the update are effective for all entities between March 12, 2020 and December 31, 2022. The Company has established a cross-functional working group to guide the Company’s transition from LIBOR and has begun efforts to transition to alternative rates consistent with industry timelines. The Company has identified its products that utilize LIBOR and has implemented enhanced fallback language to facilitate the transition to alternative reference rates. The Company is evaluating existing platforms and systems and preparing to offer new rates. In December 2019, FASB released ASU 2019-12 - Income Taxes (Topic 740) , which simplifies the accounting for income taxes by removing multiple exceptions to the general principals in Topic 740. The standard is effective for public business entities for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2020. The Company does not expect the adoption of this standard to have a material impact on the Company’s Consolidated Financial Statements.

ACQUISITION OF REVERE BANK (Tab

ACQUISITION OF REVERE BANK (Tables)	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Provisional fair values of acquired identifiable assets and liabilities assumed	The consideration paid for Revere’s common equity and outstanding stock options and the provisional fair values of acquired identifiable assets and assumed identifiable liabilities as of December 31, 2020 were as follows: (Dollars in thousands, except per share data) December 31, 2020 Purchase price: Fair value of common shares issued (12,768,949 shares) based on Sandy Spring's share price of $22.64 $ 289,089 Fair value of Revere stock options converted to Sandy Spring stock options 3,611 Cash paid for cashed-out Revere stock options 291 Cash for fractional shares 11 Total purchase price $ 293,002 Identifiable assets: Cash and cash equivalents $ 80,744 Investments available-for-sale 180,752 Loans 2,502,244 Premises and equipment 3,443 Accrued interest receivable 7,651 Core deposit intangible asset 18,360 Other assets 53,162 Total identifiable assets $ 2,846,356 Identifiable liabilities: Deposits $ 2,322,422 Borrowings 205,514 Other liabilities 25,933 Total identifiable liabilities $ 2,553,869 Provisional fair value of net assets acquired including identifiable intangible assets 292,487 Provisional resulting goodwill $ 515

INVESTMENTS (Tables)

INVESTMENTS (Tables)	12 Months Ended
	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Amortized cost and Estimated fair values of Investments Available-for-sale	The amortized cost and estimated fair values of investments available-for-sale at December 31 are presented in the following table: 2020 2019 Amortized Cost Gross Unrealized Gross Unrealized Estimated Fair Amortized Cost Gross Unrealized Gross Unrealized Estimated Fair U.S. treasuries and government agencies $ 42,750 $ 549 $ (2) $ 43,297 $ 260,294 $ 887 $ (2,686) $ 258,495 State and municipal 377,108 13,470 (211) 390,367 229,309 4,377 (37) 233,649 Mortgage-backed and asset-backed 881,201 24,078 (847) 904,432 568,373 3,268 (882) 570,759 Corporate debt 9,100 825 — 9,925 9,100 452 — 9,552 Trust preferred — — — — 310 — — 310 Total debt securities 1,310,159 38,922 (1,060) 1,348,021 1,067,386 8,984 (3,605) 1,072,765 Marketable equity securities — — — — 568 — — 568 Total investments available-for-sale $ 1,310,159 $ 38,922 $ (1,060) $ 1,348,021 $ 1,067,954 $ 8,984 $ (3,605) $ 1,073,333
Gross Unrealized Losses and Fair Value by Length of Time	Gross unrealized losses and fair values by length of time that individual available-for-sale securities have been in an unrealized loss position at December 31 are presented in the following tables: December 31, 2020 Number Less Than 12 Months 12 Months or More Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses U.S. treasuries and government agencies 2 $ 25,369 $ 2 $ — $ — $ 25,369 $ 2 State and municipal 8 22,753 211 — — 22,753 211 Mortgage-backed and asset-backed 24 44,746 154 76,879 693 121,625 847 Total 34 $ 92,868 $ 367 $ 76,879 $ 693 $ 169,747 $ 1,060 December 31, 2019 Number Less Than 12 Months 12 Months or More Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses U.S. treasuries and government agencies 12 $ 133,221 $ 2,211 $ 17,911 $ 475 $ 151,132 $ 2,686 State and municipal 3 7,227 37 — — 7,227 37 Mortgage-backed and asset-backed 35 107,917 508 76,867 374 184,784 882 Total 50 $ 248,365 $ 2,756 $ 94,778 $ 849 $ 343,143 $ 3,605
Estimated fair values of debt securities available-for-sale by contractual maturity	The estimated fair values and amortized costs of debt securities available-for-sale by contractual maturity at December 31 are provided in the following table: December 31, 2020 December 31, 2019 (In thousands) Fair Value Amortized Cost Fair Value Amortized Cost U.S. treasuries and government agencies: One year or less $ 33,963 $ 33,833 $ 69,799 $ 69,330 One to five years 9,334 8,917 96,709 96,507 Five to ten years — — — — After ten years — — 91,987 94,457 State and municipal: One year or less 16,581 16,458 33,311 33,054 One to five years 44,910 43,857 76,723 75,432 Five to ten years 59,059 56,130 75,820 73,741 After ten years 269,817 260,663 47,795 47,082 Mortgage-backed and asset-backed: One year or less 1 1 852 822 One to five years 21,637 21,229 7,125 6,969 Five to ten years 74,142 72,481 55,226 54,799 After ten years 808,652 787,490 507,556 505,783 Corporate debt: One year or less — — — — One to five years 2,318 2,100 — — Five to ten years 7,607 7,000 9,552 9,100 After ten years — — — — Trust preferred: One year or less — — — — One to five years — — — — Five to ten years — — — — After ten years — — 310 310 Total available-for-sale debt securities $ 1,348,021 $ 1,310,159 $ 1,072,765 $ 1,067,386
Other Equity Securities	Other equity securities at the dates indicated are presented in the following table: (In thousands) 2020 2019 Federal Reserve Bank stock $ 38,650 $ 22,559 Federal Home Loan Bank of Atlanta stock 26,433 29,244 Other equity securities 677 — Total equity securities $ 65,760 $ 51,803
Gross Realized Gains and Losses on All Investments	Gross realized gains and losses on all investments for the years ended December 31 are presented in the following table: (In thousands) 2020 2019 2018 Gross realized gains from sales of investments available-for-sale $ 1,297 $ 14 $ 2,519 Gross realized losses from sales of investments available-for-sale (1,068) (2) (2,343) Net gains from calls of investments available-for-sale 238 65 14 Net investment securities gains $ 467 $ 77 $ 190

LOANS (Tables)

LOANS (Tables)	12 Months Ended
	Dec. 31, 2020
Receivables [Abstract]
Loan Portfolio Segment Balances	The loan portfolio segment balances at December 31 are presented in the following table: (In thousands) 2020 2019 Commercial real estate: Commercial investor real estate $ 3,634,720 $ 2,169,156 Commercial owner-occupied real estate 1,642,216 1,288,677 Commercial AD&C 1,050,973 684,010 Commercial business 2,267,548 801,019 Total commercial loans 8,595,457 4,942,862 Residential real estate: Residential mortgage 1,105,179 1,149,327 Residential construction 182,619 146,279 Consumer 517,254 466,764 Total residential and consumer loans 1,805,052 1,762,370 Total loans $ 10,400,509 $ 6,705,232
Loans To Related Parties	Certain directors and executive officers have loan transactions with the Company. The following schedule summarizes changes in amounts of loans outstanding, both direct and indirect, to these persons during the periods indicated: (In thousands) 2020 2019 2018 Balance at January 1 $ 51,367 $ 54,208 $ 36,712 Additions 46,846 4,737 21,871 Repayments (2,208) (7,578) (4,375) Balance at December 31 $ 96,005 $ 51,367 $ 54,208

CREDIT QUALITY ASSESSMENT (Tabl

CREDIT QUALITY ASSESSMENT (Tables)	12 Months Ended
	Dec. 31, 2020
Credit Loss [Abstract]
Allowance For Loan Losses Roll Forward Table	Summary information on the allowance for credit loss activity for the years ended December 31 is provided in the following table: (In thousands) 2020 2019 2018 Balance at beginning of year $ 56,132 $ 53,486 $ 45,257 Initial allowance on PCD loans at adoption of ASC 326 2,762 — — Transition impact of adopting ASC 326 2,983 — — Initial allowance on Revere PCD loans 18,628 — — Provision for credit losses 85,669 4,684 9,023 Loan charge-offs (1,819) (2,668) (1,416) Loan recoveries 1,012 630 622 Net charge-offs (807) (2,038) (794) Balance at period end $ 165,367 $ 56,132 $ 53,486
Schedule of collateral dependent loans individually evaluated for credit loss	The following table provides summary information regarding collateral dependent loans individually evaluated for credit loss at the dates indicated: (In thousands) 2020 2019 Collateral dependent loans individually evaluated for credit loss with an allowance $ 20,717 $ 15,333 Collateral dependent loans individually evaluated for credit loss without an allowance 77,001 9,440 Total individually evaluated collateral dependent loans $ 97,718 $ 24,773 Allowance for credit losses related to loans evaluated individually $ 11,405 $ 5,501 Allowance for credit losses related to loans evaluated collectively 153,962 50,631 Total allowance for credit losses $ 165,367 $ 56,132
Activity in Allowance for Loan and Lease Losses by Respective Loan Portfolio Segment	The following tables provide information on the activity in the allowance for credit losses by the respective loan portfolio segment for the years ended December 31: 2020 Commercial Real Estate Residential Real Estate Commercial Commercial Commercial Commercial Residential Residential Consumer Total Balance as of December 31, 2019 $ 18,407 $ 6,884 $ 7,590 $ 11,395 $ 8,803 $ 967 $ 2,086 $ 56,132 Initial allowance on PCD loans at adoption of ASC 326 1,114 — — 1,549 — — 99 2,762 Transition impact of adopting ASC 326 (3,125) 387 2,576 2,988 (388) (275) 820 2,983 Initial allowance on Revere PCD loans 7,973 2,782 1,248 6,289 243 6 87 18,628 Provision 33,431 10,008 10,743 24,374 3,016 798 3,299 85,669 Charge-offs (411) — — (491) (484) — (433) (1,819) Recoveries 15 — — 702 105 6 184 1,012 Net (charge-offs)/ recoveries (396) — — 211 (379) 6 (249) (807) Balance at end of period $ 57,404 $ 20,061 $ 22,157 $ 46,806 $ 11,295 $ 1,502 $ 6,142 $ 165,367 Total loans $ 3,634,720 $ 1,642,216 $ 1,050,973 $ 2,267,548 $ 1,105,179 $ 182,619 $ 517,254 $ 10,400,509 Allowance for credit losses to total loans ratio 1.58 % 1.22 % 2.11 % 2.06 % 1.02 % 0.82 % 1.19 % 1.59 % Balance of loans individually evaluated for credit loss $ 45,227 $ 11,561 $ 15,044 $ 23,648 $ 1,874 $ — $ 364 $ 97,718 Allowance related to loans evaluated individually $ 1,273 $ — $ 603 $ 9,529 $ — $ — $ — $ 11,405 Individual allowance to loans evaluated individually ratio 2.81 % — % 4.01 % 40.30 % — % — % — % 11.67 % Balance of loans collectively evaluated for credit loss $ 3,589,493 $ 1,630,655 $ 1,035,929 $ 2,243,900 $ 1,103,305 $ 182,619 $ 516,890 $ 10,302,791 Allowance related to loans evaluated collectively $ 56,131 $ 20,061 $ 21,554 $ 37,277 $ 11,295 $ 1,502 $ 6,142 $ 153,962 Collective allowance to loans evaluated collectively ratio 1.56 % 1.23 % 2.08 % 1.66 % 1.02 % 0.82 % 1.19 % 1.49 % The following table provides information on the activity in the allowance for credit losses by the respective loan portfolio segment for the period indicated: 2019 Commercial Real Estate Residential Real Estate Commercial Commercial Commercial Commercial Residential Residential Consumer Balance at beginning of year $ 17,603 $ 6,307 $ 5,944 $ 11,377 $ 8,881 $ 1,261 $ 2,113 $ 53,486 Provision/ (credit) 788 577 1,418 1,164 474 (302) 565 4,684 Charge-offs — — — (1,195) (690) — (783) (2,668) Recoveries 16 — 228 49 138 8 191 630 Net (charge-offs)/ recoveries 16 — 228 (1,146) (552) 8 (592) (2,038) Balance at end of period $ 18,407 $ 6,884 $ 7,590 $ 11,395 $ 8,803 $ 967 $ 2,086 $ 56,132 Total loans $ 2,169,156 $ 1,288,677 $ 684,010 $ 801,019 $ 1,149,327 $ 146,279 $ 466,764 $ 6,705,232 Allowance for loans total loans ratio 0.85 % 0.53 % 1.11 % 1.42 % 0.77 % 0.66 % 0.45 % 0.84 % Balance of loans specifically evaluated for impairment $ 9,212 $ 4,148 $ 829 $ 8,867 $ 1,717 $ — $ — $ 24,773 Allowance for loans specifically evaluated for impairment $ 1,529 $ 23 $ 132 $ 3,817 $ — $ — $ — $ 5,501 Specific allowance to specific loans ratio 16.60 % 0.55 % 15.92 % 43.05 % — % — % — % 22.21 % Balance of loans collectively evaluated $ 2,150,400 $ 1,284,529 $ 683,181 $ 789,613 $ 1,147,602 $ 146,279 $ 465,771 $ 6,667,375 Allowance for loans collectively evaluated $ 16,878 $ 6,861 $ 7,458 $ 7,578 $ 8,803 $ 967 $ 2,086 $ 50,631 Collective allowance to collective loans ratio 0.78 % 0.53 % 1.09 % 0.96 % 0.77 % 0.66 % 0.45 % 0.76 % Balance of loans acquired with deteriorated credit quality $ 9,544 $ — $ — $ 2,539 $ 8 $ — $ 993 $ 13,084 Allowance for loans acquired with deteriorated credit quality $ — $ — $ — $ — $ — $ — $ — $ — Allowance for loans acquired with deteriorated credit quality ratio — % — % — % — % — % — % — % — %
Schedule of collateral dependent loans individually evaluated for credit loss with the associated allowances	The following table presents collateral dependent loans individually evaluated for credit losses with the associated allowances for credit losses by the applicable portfolio segment: 2020 Commercial Real Estate Residential Real Estate Total (In thousands) Commercial Commercial Commercial Commercial Residential Mortgage Residential Construction Consumer Loans individually evaluated for credit losses with an allowance: Non-accruing $ 4,913 $ — $ 1,328 $ 11,178 $ — $ — $ — $ 17,419 Restructured accruing — — — 589 — — — 589 Restructured non-accruing 699 — — 2,010 — — — 2,709 Balance $ 5,612 $ — $ 1,328 $ 13,777 $ — $ — $ — $ 20,717 Allowance $ 1,273 $ — $ 603 $ 9,529 $ — $ — $ — $ 11,405 Loans individually evaluated for credit losses without an allowance: Non-accruing $ 39,615 $ 9,315 $ 13,716 $ 9,118 $ — $ — $ — $ 71,764 Restructured accruing — — — 126 1,602 — — 1,728 Restructured non-accruing — 2,246 — 627 272 — 364 3,509 Balance $ 39,615 $ 11,561 $ 13,716 $ 9,871 $ 1,874 $ — $ 364 $ 77,001 Total individually evaluated loans: Non-accruing $ 44,528 $ 9,315 $ 15,044 $ 20,296 $ — $ — $ — $ 89,183 Restructured accruing — — — 715 1,602 — — 2,317 Restructured non-accruing 699 2,246 — 2,637 272 — 364 6,218 Balance $ 45,227 $ 11,561 $ 15,044 $ 23,648 $ 1,874 $ — $ 364 $ 97,718 Unpaid contractual principal balance $ 49,920 $ 15,309 $ 16,040 $ 30,958 $ 3,225 $ — $ 364 $ 115,816
Schedule of nonaccrual related information	The following table presents average principal balance of total non-accrual loans, contractual interest due and interest income recognized on a cash basis on non-accrual loans for the periods indicated below: 2020 Commercial Real Estate Residential Real Estate Total (In thousands) Commercial Commercial Commercial Commercial Residential Mortgage Residential Construction Consumer Average non-accrual loans for the period $ 26,849 $ 6,605 $ 4,267 $ 16,532 $ 11,634 $ — $ 6,675 $ 72,562 Contractual interest income due on non-accrual loans during the period $ 6,547 $ 2,741 $ 4,505 $ 2,858 $ 918 $ — $ 732 $ 18,301
Summary of Impaired Loans	The following tables present the recorded investment with respect to impaired loans, the associated allowance by the applicable portfolio segment and the unpaid contractual principal balance of the impaired loans: 2019 Commercial Real Estate Total Recorded Investment in Impaired (In thousands) Commercial Commercial Commercial Commercial All Impaired loans with a specific allowance: Non-accruing $ 5,448 $ 767 $ 829 $ 5,608 $ — $ 12,652 Restructured accruing — — — 266 — 266 Restructured non-accruing 437 122 — 1,856 — 2,415 Balance $ 5,885 $ 889 $ 829 $ 7,730 $ — $ 15,333 Allowance $ 1,529 $ 23 $ 132 $ 3,817 $ — $ 5,501 Impaired loans without a specific allowance: Non-accruing $ 2,552 $ 1,522 $ — $ 114 $ — $ 4,188 Restructured accruing 775 — — 151 1,444 2,370 Restructured non-accruing — 1,737 — 872 273 2,882 Balance $ 3,327 $ 3,259 $ — $ 1,137 $ 1,717 $ 9,440 Total impaired loans: Non-accruing $ 8,000 $ 2,289 $ 829 $ 5,722 $ — $ 16,840 Restructured accruing 775 — — 417 1,444 2,636 Restructured non-accruing 437 1,859 — 2,728 273 5,297 Balance $ 9,212 $ 4,148 $ 829 $ 8,867 $ 1,717 $ 24,773 Unpaid principal balance in total impaired loans $ 13,805 $ 6,072 $ 829 $ 11,296 $ 2,618 $ 34,620 2019 Commercial Real Estate Total Recorded Investment in Impaired (In thousands) Commercial Commercial Commercial Commercial Average impaired loans for the period $ 7,565 $ 4,390 $ 2,052 $ 7,781 $ 1,577 $ 23,365 Contractual interest income due on impaired loans during the period $ 786 $ 258 $ 127 $ 648 $ 128 $ 1,947 Interest income on impaired loans recognized on a cash basis $ 49 $ 187 $ — $ 221 $ 8 $ 465 Interest income on impaired loans recognized on an accrual basis $ 39 $ — $ — $ 62 $ 68 $ 169
Schedule of information on the credit quality of loan portfolio	The following tables provide information on the credit quality of the loan portfolio under the new CECL disclosure requirements for the loan portfolio by segment at December 31 for the years indicated: 2020 Commercial Real Estate Residential Real Estate (In thousands) Commercial Commercial Commercial Commercial Residential Residential Consumer Total Analysis of non-accrual loan activity: Balance at beginning of period $ 8,437 $ 4,148 $ 829 $ 8,450 $ 12,661 $ — $ 4,107 $ 38,632 PCD loans designated as non-accrual (1) 9,544 — — 2,539 8 — 993 13,084 Loans placed on non-accrual 37,882 8,572 15,844 17,442 1,485 — 4,061 85,286 Non-accrual balances transferred to OREO — — — — (70) — — (70) Non-accrual balances charged-off (411) — — (446) (416) — (121) (1,394) Net payments or draws (10,225) (1,059) (1,629) (4,169) (2,598) — (1,521) (21,201) Non-accrual loans brought current — (100) — (883) (858) — (135) (1,976) Balance at end of period $ 45,227 $ 11,561 $ 15,044 $ 22,933 $ 10,212 $ — $ 7,384 $ 112,361 (1) Upon the adoption of the CECL standard, the Company transitioned from closed pool level accounting for PCI loans during the first quarter of 2020. Non-accrual loans are determined based on the individual loan level and aggregated for reporting.
Credit Quality of Loan Portfolio by Segment	2020 Commercial Real Estate Residential Real Estate (In thousands) Commercial Commercial Commercial Commercial Residential Residential Consumer Total Performing loans: Current $ 3,571,184 $ 1,624,265 $ 1,033,057 $ 2,238,617 $ 1,073,963 $ 182,557 $ 502,548 $ 10,226,191 30-59 days 14,046 6,390 29 4,859 16,213 — 5,275 46,812 60-89 days 4,130 — 2,843 263 2,709 62 2,047 12,054 Total performing loans 3,589,360 1,630,655 1,035,929 2,243,739 1,092,885 182,619 509,870 10,285,057 Non-performing loans: Non-accrual loans 45,227 11,561 15,044 22,933 10,212 — 7,384 112,361 Loans greater than 90 days past due 133 — — 161 480 — — 774 Restructured loans — — — 715 1,602 — — 2,317 Total non-performing loans 45,360 11,561 15,044 23,809 12,294 — 7,384 115,452 Total loans $ 3,634,720 $ 1,642,216 $ 1,050,973 $ 2,267,548 $ 1,105,179 $ 182,619 $ 517,254 $ 10,400,509 2019 Commercial Real Estate (In thousands) Commercial Commercial Commercial Commercial Pass $ 2,146,971 $ 1,278,337 $ 683,181 $ 783,909 $ 4,892,398 Special Mention 3,189 2,284 — 2,487 7,960 Substandard 18,996 8,056 829 14,623 42,504 Doubtful — — — — — Total $ 2,169,156 $ 1,288,677 $ 684,010 $ 801,019 $ 4,942,862 2019 Residential Real Estate (In thousands) Residential Residential Consumer Performing $ 1,135,586 $ 146,279 $ 462,293 $ 1,744,158 Non-performing: 90 days past due — — — — Non-accruing 12,661 — 4,107 16,768 Restructured loans 1,080 — 364 1,444 Total $ 1,149,327 $ 146,279 $ 466,764 $ 1,762,370
Credit Risk Rating Indicators	The following table provides information about credit quality indicators by the year of origination: 2020 Term Loans by Origination Year Revolving (In thousands) 2020 2019 2018 2017 2016 Prior Loans Total Commercial Investor R/E: Pass $ 910,426 $ 763,214 $ 448,406 $ 448,698 $ 469,077 $ 498,384 $ 33,531 $ 3,571,736 Special Mention 11,044 — 4,879 833 269 27 — 17,052 Substandard 589 4,245 13,649 20,619 673 6,157 — 45,932 Doubtful — — — — — — — — Total $ 922,059 $ 767,459 $ 466,934 $ 470,150 $ 470,019 $ 504,568 $ 33,531 $ 3,634,720 Commercial Owner-Occupied R/E: Pass $ 285,310 $ 385,058 $ 234,578 $ 192,634 $ 204,925 $ 306,840 $ 1,664 $ 1,611,009 Special Mention 2,290 — 3,027 4,742 134 4,079 — 14,272 Substandard 1,610 4,335 2,065 465 219 8,009 — 16,703 Doubtful — — — — — 232 — 232 Total $ 289,210 $ 389,393 $ 239,670 $ 197,841 $ 205,278 $ 319,160 $ 1,664 $ 1,642,216 Commercial AD&C: Pass $ 485,631 $ 261,537 $ 149,703 $ 50,192 $ 89 $ 2,357 $ 80,764 $ 1,030,273 Special Mention 1,711 — — — — — — 1,711 Substandard 1,439 891 — 13,816 2,843 — — 18,989 Doubtful — — — — — — — — Total $ 488,781 $ 262,428 $ 149,703 $ 64,008 $ 2,932 $ 2,357 $ 80,764 $ 1,050,973 Commercial Business: Pass $ 1,244,822 $ 208,682 $ 138,861 $ 86,830 $ 34,498 $ 81,760 $ 433,016 $ 2,228,469 Special Mention 1,929 1,382 1,119 708 309 621 4,319 10,387 Substandard 2,914 4,564 3,519 1,631 2,745 3,456 1,829 20,658 Doubtful 106 995 849 36 1,284 1,852 2,912 8,034 Total $ 1,249,771 $ 215,623 $ 144,348 $ 89,205 $ 38,836 $ 87,689 $ 442,076 $ 2,267,548 Residential Mortgage: Beacon score: 660-850 $ 229,033 $ 74,054 $ 138,824 $ 172,493 $ 129,701 $ 251,065 $ — $ 995,170 600-659 4,824 7,706 10,763 11,719 8,173 21,424 — 64,609 540-599 350 1,238 5,219 2,608 4,791 10,167 — 24,373 less than 540 2,702 2,108 3,576 2,150 892 9,599 — 21,027 Total $ 236,909 $ 85,106 $ 158,382 $ 188,970 $ 143,557 $ 292,255 $ — $ 1,105,179 Residential Construction: Beacon score: 660-850 $ 112,604 $ 44,647 $ 14,543 $ 2,805 $ 1,693 $ — $ 172 $ 176,464 600-659 1,743 3,189 — — — — — 4,932 540-599 — — — — 369 — — 369 less than 540 854 — — — — — — 854 Total $ 115,201 $ 47,836 $ 14,543 $ 2,805 $ 2,062 $ — $ 172 $ 182,619 Consumer: Beacon score: 660-850 $ 2,575 $ 4,609 $ 5,112 $ 2,110 $ 2,614 $ 24,444 $ 417,737 $ 459,201 600-659 374 445 334 428 467 5,401 21,052 28,501 540-599 89 1,216 294 339 601 3,926 6,153 12,618 less than 540 751 160 525 785 532 2,826 11,355 16,934 Total $ 3,789 $ 6,430 $ 6,265 $ 3,662 $ 4,214 $ 36,597 $ 456,297 $ 517,254 Total loans $ 3,305,720 $ 1,774,275 $ 1,179,845 $ 1,016,641 $ 866,898 $ 1,242,626 $ 1,014,504 $ 10,400,509
Historical Information On The Credit Quality Of The Loan Portfolio Under The Legacy Disclosure	The following section provides historical information on the credit quality of the loan portfolio under the legacy disclosure requirements: 2019 Commercial Real Estate Residential Real Estate (In thousands) Commercial Commercial Commercial Commercial Residential Residential Consumer Total Non-performing loans and assets: Non-accrual loans $ 8,437 $ 4,148 $ 829 $ 8,450 $ 12,661 $ — $ 4,107 $ 38,632 Loans 90 days past due — — — — — — — — Restructured loans 775 — — 417 1,080 — 364 2,636 Total non-performing loans 9,212 4,148 829 8,867 13,741 — 4,471 41,268 Other real estate owned 409 — 665 39 305 — 64 1,482 Total non-performing assets $ 9,621 $ 4,148 $ 1,494 $ 8,906 $ 14,046 $ — $ 4,535 $ 42,750 2019 Commercial Real Estate Residential Real Estate (In thousands) Commercial Commercial Commercial Commercial Residential Residential Consumer Past due loans: 30-59 days $ 932 $ 316 $ — $ 908 $ 14,853 $ 280 $ 2,697 $ 19,986 60-89 days — — — 370 4,541 1,334 1,517 7,762 > 90 days — — — — — — — — Total past due 932 316 — 1,278 19,394 1,614 4,214 27,748 Non-accrual loans 8,437 4,148 829 8,450 12,661 — 4,107 38,632 Loans acquired with deteriorated credit quality 9,544 — — 2,539 8 — 993 13,084 Current loans 2,150,243 1,284,213 683,181 788,752 1,117,264 144,665 457,450 6,625,768 Total loans $ 2,169,156 $ 1,288,677 $ 684,010 $ 801,019 $ 1,149,327 $ 146,279 $ 466,764 $ 6,705,232
Restructured Loans for Specific Segments of Loan Portfolio	The following table provides the amounts of the restructured loans at the date of restructuring for specific segments of the loan portfolio during the period indicated: For the Year Ended December 31, 2020 Commercial Real Estate (In thousands) Commercial Commercial Commercial Commercial All Other Total Troubled debt restructurings: Restructured accruing $ — $ — $ — $ 380 $ 549 $ 929 Restructured non-accruing 723 930 — 1,951 — 3,604 Balance $ 723 $ 930 $ — $ 2,331 $ 549 $ 4,533 Specific allowance $ 65 $ — $ — $ 955 $ — $ 1,020 Restructured and subsequently defaulted $ — $ — $ — $ — $ — $ — For the Year Ended December 31, 2019 Commercial Real Estate (In thousands) Commercial Commercial Commercial Commercial All Other Total Troubled debt restructurings: Restructured accruing $ 775 $ — $ — $ 170 $ 364 $ 1,309 Restructured non-accruing 789 — — 261 — 1,050 Balance $ 1,564 $ — $ — $ 431 $ 364 $ 2,359 Specific allowance $ 205 $ — $ — $ 196 $ — $ 401 Restructured and subsequently defaulted $ — $ — $ — $ — $ — $ —

PREMISES AND EQUIPMENT (Tables)

PREMISES AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Components of premises and equipment	Presented in the following table are the components of premises and equipment at December 31: (In thousands) 2020 2019 Land $ 13,262 $ 10,160 Buildings and leasehold improvements 70,776 70,812 Equipment 49,614 46,471 Total premises and equipment 133,652 127,443 Less: accumulated depreciation and amortization (75,932) (68,828) Net premises and equipment $ 57,720 $ 58,615

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Lease, Cost	The following table provides information regarding the Company's leases as of the dates indicated: Year Ended 2020 2019 Components of lease expense: Operating lease cost (resulting from lease payments) $ 12,453 $ 11,334 Supplemental cash flow information related to leases: Operating cash flows from operating leases $ 13,571 $ 8,704 ROU assets obtained in the exchange for lease liabilities due to: New leases $ 871 $ 399 Acquisitions $ 7,720 $ — As of December 31, 2020 December 31, 2019 Supplemental balance sheet information related to leases: Operating lease ROU assets $ 65,215 $ 69,320 Operating lease liabilities $ 74,982 $ 76,871 Other information related to leases: Weighted average remaining lease term of operating leases 9.5 years 10.4 years Weighted average discount rate of operating leases 3.04 % 3.28 %
Schedule of maturities of operating lease liabilities	(In thousands) Amount Maturity: One year $ 12,490 Two years 10,946 Three years 10,851 Four years 9,063 Five years 7,347 Thereafter 37,382 Total undiscounted lease payments 88,079 Less: Present value discount (13,097) Lease Liability $ 74,982

GOODWILL AND OTHER INTANGIBLE_2

GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Gross Carrying Amounts and Accumulated Amortization of Intangible Assets and Goodwill	The gross carrying amounts and accumulated amortization of intangible assets and goodwill are presented at December 31 in the following table: 2020 Weighted 2019 Weighted Gross Net Average Gross Net Average Carrying Accumulated Carrying Remaining Carrying Accumulated Carrying Remaining (Dollars in thousands) Amount Amortization Amount Life Amount Amortization Amount Life Amortizing intangible assets: Core deposit intangibles $ 29,038 $ (7,969) $ 21,069 8.4 years $ 10,678 $ (3,689) $ 6,989 8.0 years Other identifiable intangibles 13,906 (2,454) 11,452 10.7 years 1,478 (626) 852 9.7 years Total amortizing intangible assets $ 42,944 $ (10,423) $ 32,521 $ 12,156 $ (4,315) $ 7,841 Goodwill $ 370,223 $ 370,223 $ 347,149 $ 347,149
Net carrying amount of goodwill by segment	The following table presents the net carrying amount of goodwill by segment for the periods indicated: (In thousands) Community Investment Balance December 31, 2018 $ 331,173 $ 6,788 $ 9,188 $ 347,149 No Activity — — — — Balance December 31, 2019 331,173 6,788 9,188 347,149 Acquisition of Rembert Pendleton Jackson — — 22,559 22,559 Acquisition of Revere Bank 515 — — 515 Balance December 31, 2020 $ 331,688 $ 6,788 $ 31,747 $ 370,223
Estimated Future Amortization Expense for Amortizing Intangibles	The following table presents the estimated future amortization expense for amortizing intangible assets within the years ending December 31: (In thousands) Amount 2021 $ 6,600 2022 5,844 2023 5,089 2024 4,333 2025 3,567 Thereafter 7,088 Total amortizing intangible assets $ 32,521

DEPOSITS (Tables)

DEPOSITS (Tables)	12 Months Ended
	Dec. 31, 2020
Deposits [Abstract]
Composition of Deposits	The following table presents the composition of deposits at December 31 for the years indicated: (In thousands) 2020 2019 Noninterest-bearing deposits $ 3,325,547 $ 1,892,052 Interest-bearing deposits: Demand 1,292,164 836,433 Money market savings 3,339,645 1,839,593 Regular savings 418,051 329,919 Time deposits of less than $100,000 509,919 463,431 Time deposits greater than $100,000 and less than $250,000 670,717 682,936 Time deposits of $250,000 or more 477,026 395,955 Total interest-bearing deposits 6,707,522 4,548,267 Total deposits $ 10,033,069 $ 6,440,319
Maturity schedule for time deposits maturing within years	The following table presents the maturity schedule for time deposits maturing within years ending December 31: (In thousands) Amount 2021 $ 1,208,915 2022 275,872 2023 84,093 2024 73,859 2025 14,745 Thereafter 178 Total time deposits $ 1,657,662
Months to maturities of time deposits	The Company's time deposits of $100,000 to $250,000 represented 6.7% of total deposits and time deposits of $250,000 or more represented 4.8% of total deposits at December 31, 2020 and are presented by maturity in the following table: Months to Maturity (In thousands) 3 or Less Over 3 to 6 Over 6 to 12 Over 12 Total Time deposits - $100,000 to $250,000 $ 211,006 $ 127,934 $ 139,133 $ 192,644 $ 670,717 Time deposits - $250,000 or more $ 111,332 $ 115,678 $ 140,231 $ 109,785 $ 477,026

BORROWINGS (Tables)

BORROWINGS (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of Subordinated Borrowing	The following table provides information on subordinated debentures for the period indicated: (In thousands) 2020 2019 Fixed to floating rate sub debt, 4.25% $ 175,000 $ 175,000 WashingtonFirst sub debt, 4.81% 25,000 25,000 Revere fixed to floating rate sub debt, 5.625% 31,000 — Total Sub debt 231,000 200,000 Less: WashingtonFirst and Revere sub debt held as investments by Sandy Spring (3,000) — Add: Purchase accounting premium 1,669 1,894 Less: Debt issuance costs (2,581) (2,885) Net sub debt 227,088 199,009 WashingtonFirst callable junior subordinated debt — 10,310 Add: Purchase accounting premium — 87 Net WashingtonFirst callable junior subordinated debt — 10,397 Long-term borrowings $ 227,088 $ 209,406
Retail Repurchase Agreements And Other Short-Term Borrowings	Information relating to retail repurchase agreements and federal funds purchased is presented in the following table at and for the years ending December 31: 2020 2019 2018 (Dollars in thousands) Amount Rate Amount Rate Amount Rate End of period: Retail repurchase agreements $ 153,157 0.11 % $ 138,605 0.58 % $ 137,429 0.51 % Federal funds purchased 390,000 0.10 75,000 1.62 — — Average for the year: Retail repurchase agreements $ 142,283 0.32 % $ 134,070 0.54 % $ 142,938 0.34 % Federal funds purchased 367,240 0.41 17,373 2.43 — — Maximum month-end balance: Retail repurchase agreements $ 153,157 $ 152,685 $ 154,435 Federal funds purchased 921,289 75,000 —
Borrowings	Advances from the FHLB and the respective maturity schedule at December 31 for the years indicated consisted of the following: 2020 2019 (Dollars in thousands) Amounts Weighted Average Amounts Weighted Average Maturity: One year $ 230,243 2.39 % $ 134,167 2.13 % Two years 76,332 2.37 230,445 2.39 Three years 72,500 3.12 76,665 2.37 Four years — — 72,500 3.12 Five years — — — — After five years — — — — Total advances from FHLB $ 379,075 2.52 $ 513,777 2.42

SHARE BASED COMPENSATION (Table

SHARE BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Fair Values of all Options Granted Estimated Using Binomial Option-Pricing Model with Weighted-average Assumptions	The fair values of all of the options granted for the periods indicated have been estimated using a binomial option-pricing model with the weighted-average assumptions for the years ended December 31 are presented in the following table: 2020 2019 2018 Dividend yield — % — % 2.64 % Weighted average expected volatility — % — % 39.13 % Weighted average risk-free interest rate — % — % 2.61 % Weighted average expected lives (in years) 0 0 5.61 years Weighted average grant-date fair value $ — $ — $ 11.73
Summary of Share Option Activity	A summary of share option activity for the period indicated is reflected in the following table: Number Weighted Average Exercise Weighted Average Contractual Remaining Life (Years) Aggregate Intrinsic Balance at January 1, 2020 65,279 $ 31.34 $ 485 Granted — $ — Converted options from Revere acquisition 395,298 $ 12.27 Exercised (26,063) $ 12.10 $ 398 Forfeited (765) $ 39.02 Expired (3,711) $ 30.46 Balance at December 31, 2020 430,038 $ 14.97 3.0 years $ 6,828 Exercisable at December 31, 2020 425,274 $ 14.71 3.0 years $ 6,828
Summary of Activity for Company's Restricted Stock	A summary of the activity for the Company’s restricted stock for the period indicated is presented in the following table: (In dollars, except share data): Number Weighted Average Grant-Date Fair Value Restricted stock at January 1, 2020 226,502 $ 35.43 Granted 246,015 $ 25.82 Vested (66,533) $ 34.38 Forfeited (14,301) $ 37.47 Restricted stock at December 31, 2020 391,683 $ 29.50

PENSION, PROFIT SHARING, AND _2

PENSION, PROFIT SHARING, AND OTHER EMPLOYEE BENEFIT PLANS (Tables)	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
The Plan's Funded Status	The Pension Plan’s funded status at December 31 is as follows: (In thousands) 2020 2019 Reconciliation of Projected Benefit Obligation: Projected obligation at January 1 $ 45,497 $ 40,152 Interest cost 1,437 1,609 Actuarial loss 290 371 Benefit payments (1,470) (1,695) Increase related to change in assumptions 6,672 5,060 Projected obligation at December 31 52,426 45,497 Reconciliation of Fair Value of Plan Assets: Fair value of plan assets at January 1 43,457 37,772 Actual return on plan assets 6,370 7,195 Contribution — 185 Benefit payments (1,470) (1,695) Fair value of plan assets at December 31 $ 48,357 $ 43,457 Funded status at December 31 $ (4,069) $ (2,040) Accumulated benefit obligation at December 31 $ 52,426 $ 45,497 Unrecognized net actuarial loss $ 12,719 $ 11,177 Net periodic pension cost not yet recognized $ 12,719 $ 11,177
Weighted-Average Assumptions Used To Determine Benefit Obligations	Weighted average assumptions used to determine benefit obligations at December 31 are presented in the following table: 2020 2019 2018 Discount rate 2.50% 3.25% 4.15% Rate of compensation increase N/A N/A N/A
Net Periodic Benefit Cost	The components of net periodic benefit cost for the years ended December 31 are presented in the following table: (In thousands) 2020 2019 2018 Interest cost on projected benefit obligation $ 1,437 $ 1,609 $ 1,540 Expected return on plan assets (1,821) (1,647) (1,861) Recognized net actuarial loss 874 1,059 1,000 Net periodic benefit cost $ 490 $ 1,021 $ 679
Weighted-Average Assumptions Used To Determine Net Periodic Benefit Cost	Weighted average assumptions used to determine net periodic benefit cost for years ended December 31 are presented in the following table: 2020 2019 2018 Discount rate 3.25% 4.15% 3.65% Expected return on plan assets 4.75% 5.00% 5.00% Rate of compensation increase N/A N/A N/A
Components Of Net Unrecognized Benefits Costs That Is Reflected In Accumulated Other Comprehensive Income (Loss)	Reclassifications represent the portion of the unrecognized benefits that are recognized each period as a component of the net periodic benefit cost. (In thousands) Unrecognized Net Included in accumulated other comprehensive loss at January 1, 2018 $ 12,487 Reductions during the year 3,914 Reclassifications due to recognition as net periodic pension cost (1,000) Increase related to change in assumptions (3,049) Included in accumulated other comprehensive loss as of December 31, 2018 12,352 Additions during the year (5,176) Reclassifications due to recognition as net periodic pension cost (1,059) Decrease related to change in assumptions 5,060 Included in accumulated other comprehensive loss as of December 31, 2019 11,177 Reductions during the year (4,256) Reclassifications due to recognition as net periodic pension cost (874) Increase related to change in assumptions 6,672 Included in accumulated other comprehensive loss as of December 31, 2020 12,719 Applicable tax effect (3,249) Included in accumulated other comprehensive loss net of tax effect at December 31, 2020 $ 9,470 Amount expected to be recognized as part of net periodic pension cost in the next fiscal year $ 931
Component of Net Periodic Benefit	The following items have not yet been recognized as a component of net periodic benefit cost at December 31: (In thousands) 2020 2019 2018 Net actuarial loss $ 12,719 $ 11,177 $ 12,352 Net periodic benefit cost not yet recognized $ 12,719 $ 11,177 $ 12,352
Pension Plan Weighted Average Allocations	The Company’s Pension Plan weighted average allocations at December 31 are presented in the following table: 2020 2019 Asset Category: Equity Securities Mutual Funds 11.6 % 10.4 % Fixed Income Mutual Funds 88.4 % 89.6 % Total pension plan assets 100.0 % 100.0 %
Fair Values Of Pension Plan Assets By Asset Category	The fair values of the Company’s Pension Plan assets by asset category at December 31 are presented in the following tables: 2020 (In thousands) Quoted Prices in Active Markets for Significant Other Significant Total Asset Category: Mutual funds: Large cap U.S. equity funds $ 2,779 $ 543 $ — $ 3,322 Small/Mid cap U.S. equity funds — 1,124 — 1,124 International equity funds 1,183 — — 1,183 Short-term fixed income funds — 4,299 — 4,299 Fixed income funds 10,724 27,705 — 38,429 Total mutual funds 14,686 33,671 — 48,357 Total pension plan assets $ 14,686 $ 33,671 $ — $ 48,357 2019 (In thousands) Quoted Prices In Active Markets for Significant Other Significant Total Asset Category: Mutual funds: Large cap U.S. equity funds $ 1,855 $ 919 $ — $ 2,774 Small/Mid cap U.S. equity funds — 847 — 847 International equity funds 894 — — 894 Short-term fixed income funds — 3,688 — 3,688 Fixed income funds 8,769 26,485 — 35,254 Total mutual funds 11,518 31,939 — 43,457 Total pension plan assets $ 11,518 $ 31,939 $ — 43,457
Benefit Payments	Benefit payments, which reflect expected future service, as appropriate, that are expected to be paid for the years ending December 31 are presented in the following table: (In thousands) Pension Benefits 2021 $ 3,340 2022 2,590 2023 2,190 2024 3,260 2025 2,410 Thereafter 15,270

OTHER NON-INTEREST INCOME AND_2

OTHER NON-INTEREST INCOME AND OTHER NON-INTEREST EXPENSE (Tables)	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
Selected components of other non-interest income and other non-interest expense	(In thousands) 2020 2019 2018 Letter of credit fees $ 710 $ 389 $ 611 Extension fees 1,967 1,287 873 Swap fee income 1,607 1,932 — Loan prepayment penalties 961 404 594 Other income 3,976 4,768 5,048 Total other non-interest income $ 9,221 $ 8,780 $ 7,126 (In thousands) 2020 2019 2018 Postage and delivery $ 1,624 $ 1,502 $ 1,439 Communications 2,729 2,414 2,610 Loss on FHLB redemption 5,928 — — Mortgage processing expense, net 1,381 817 53 Online services 1,591 1,375 1,263 Provision for credit losses on unfunded loan commitments 1,576 — — Franchise taxes 1,574 1,307 2,143 Insurance 1,311 1,113 1,043 Card transaction expense 1,083 1,031 961 Office supplies 912 957 951 Other expenses 10,894 9,910 9,029 Total other non-interest expense $ 30,603 $ 20,426 $ 19,492

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Components of income tax expense (benefit)	The following table provides the components of income tax expense for the years ended December 31: (In thousands) 2020 2019 2018 Current income taxes: Federal $ 43,115 $ 28,404 $ 18,615 State 13,785 6,598 7,183 Total current 56,900 35,002 25,798 Deferred income taxes: Federal (22,793) 234 4,808 State (6,636) 1,192 1,218 Total deferred (29,429) 1,426 6,026 Total income tax expense $ 27,471 $ 36,428 $ 31,824
Deferred tax assets and liabilities	Deferred tax assets and liabilities, shown as the sum of the appropriate tax effect for each significant type of temporary difference, are presented in the following table at December 31 for the years indicated: (In thousands) 2020 2019 Deferred tax assets: Allowance for credit losses $ 42,231 $ 14,287 Lease liability 19,192 19,616 Fair value acquisition adjustments — 1,322 Employee benefits 6,108 4,535 Unrealized losses on pension plan 3,249 2,845 Deferred loan fees and costs 4,486 471 Equity based compensation 1,856 659 Losses on other real estate owned 203 201 Other than temporary impairment 75 76 Loan and deposit premium/discount 1,081 1,422 Reserve for recourse loans 546 166 Net operating loss carryforward 1,475 916 Other 181 159 Gross deferred tax assets 80,683 46,675 Valuation allowance (1,479) (880) Net deferred tax asset 79,204 45,795 Deferred tax liabilities: Right of use asset (16,693) (17,688) Unrealized gains on investments available-for-sale (9,684) (1,379) Pension plan costs (2,211) (2,373) Depreciation (2,950) (2,744) Intangible assets (6,894) (3,338) Bond accretion (195) (322) Section 481 adjustments (669) (1,335) Fair value acquisition adjustments (555) — Other (567) (585) Gross deferred tax liabilities (40,418) (29,764) Net deferred tax asset $ 38,786 $ 16,031
Reconcilements between statutory federal income tax rate and effective tax rate	The reconcilements between the statutory federal income tax rate and the effective rate for the years ended December 31 are presented in the following table: (Dollars in thousands) 2020 2019 2018 Amount Percentage of Amount Percentage of Amount Percentage of Income tax expense at federal statutory rate $ 26,130 21.0 % $ 32,101 21.0 % $ 27,865 21.0 % Increase/ (decrease) resulting from: Tax exempt income, net (2,472) (2.0) (2,101) (1.4) (2,427) (1.8) Bank-owned life insurance (567) (0.5) (665) (0.4) (909) (0.7) State income taxes, net of federal income tax benefits 5,648 4.5 6,154 4.0 6,637 5.0 Federal tax law change (1,764) (1.4) — — — — Other, net 496 0.5 939 0.6 658 0.5 Total income tax expense and rate $ 27,471 22.1 % $ 36,428 23.8 % $ 31,824 24.0 %

NET INCOME PER COMMON SHARE (Ta

NET INCOME PER COMMON SHARE (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Calculation of Net Income Per Common Share	The calculation of net income per common share for the years ended December 31 is presented in the following table: (Dollars and amounts in thousands, except per share data) 2020 2019 2018 Net income $ 96,953 $ 116,433 $ 100,864 Less: Distributed and undistributed earnings allocated to participating securities (783) (762) (579) Net income attributable to common shareholders $ 96,170 $ 115,671 $ 100,285 Total weighted average outstanding shares 44,312 35,797 35,707 Less: Weighted average participating securities (365) (235) (205) Basic weighted average common shares 43,947 35,562 35,502 Dilutive weighted average common stock equivalents 185 56 21 Diluted weighted average common shares 44,132 35,618 35,523 Basic net income per common share $ 2.19 $ 3.25 $ 2.82 Diluted net income per common share $ 2.18 $ 3.25 $ 2.82 Anti-dilutive shares 17 9 7

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Net Accumulated Other Comprehensive Income (Loss)	The following table presents the activity in net accumulated other comprehensive income/ (loss) for the periods indicated: Unrealized Gains/ Balance at January 1, 2018 $ 687 $ (7,544) $ (6,857) Period change, net of tax (7,465) 45 (7,420) Reclassification of tax effects from other comprehensive income 148 (1,625) (1,477) Balance at December 31, 2018 (6,630) (9,124) (15,754) Period change, net of tax 10,630 792 11,422 Balance at December 31, 2019 4,000 (8,332) (4,332) Period change, net of tax 24,175 (1,138) 23,037 Balance at December 31, 2020 $ 28,175 $ (9,470) $ 18,705
Schedule of Amounts Recognized in Other Comprehensive Income (Loss)	The following table provides the information on the reclassification adjustments out of accumulated other comprehensive income/ (loss) for the periods indicated: Year Ended December 31, (In thousands) 2020 2019 2018 Unrealized gains/ (losses) on investments available-for-sale: Affected line item in the Consolidated Statements of Income: Investment securities gains $ 467 $ 77 $ 190 Income before taxes 467 77 190 Tax expense 120 20 50 Net income $ 347 $ 57 $ 140 Amortization of defined benefit pension plan items: Affected line item in the Consolidated Statements of Income: Recognized actuarial loss (1) $ (874) $ (1,059) $ (1,000) Income before taxes (874) (1,059) (1,000) Tax benefit (223) (277) (261) Net loss $ (651) $ (782) $ (739) (1) This amount is included in the computation of net periodic benefit cost, see Note 14.

DERIVATIVES (Tables)

DERIVATIVES (Tables)	12 Months Ended
	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	A summary of the Company’s interest rate swaps at December 31 for the years indicated is included in the following table: 2020 Notional Amount Estimated Fair Value Years to Maturity Receive Pay Interest rate swap agreements: Pay fixed/receive variable swaps $ 160,261 $ (9,183) 8.7 years 2.39 % 3.72 % Pay variable/receive fixed swaps 160,261 9,183 8.7 years 3.72 % 2.39 % Total swaps $ 320,522 $ — 8.7 years 3.06 % 3.06 % 2019 Notional Amount Estimated Fair Value Years to Maturity Receive Pay Interest rate swap agreements: Pay fixed/receive variable swaps $ 102,337 $ (2,507) 9.1 years 3.40 % 4.11 % Pay variable/receive fixed swaps 102,337 2,507 9.1 years 4.11 % 3.40 % Total swaps $ 204,674 $ — 9.1 years 3.76 % 3.76 %

FINANCIAL INSTRUMENTS WITH OF_2

FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK (Tables)	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Disclosure [Abstract]
Financial Instruments With Off Balance Sheet Credit Risk	A summary of the financial instruments with off-balance sheet credit risk is as follows at December 31 for the years indicated: (In thousands) 2020 2019 Commercial real estate development and construction $ 871,290 $ 571,368 Residential real estate-development and construction 94,096 89,224 Real estate-residential mortgage 335,288 74,282 Lines of credit, principally home equity and business lines 1,947,706 1,400,038 Standby letters of credit 71,777 62,065 Total Commitments to extend credit and available credit lines $ 3,320,157 $ 2,196,977

FAIR VALUE (Tables)

FAIR VALUE (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement: 2020 (In thousands) Quoted Prices in Significant Other Significant Total Assets Residential mortgage loans held for sale (1) $ — $ 78,294 $ — $ 78,294 Investments available-for-sale: U.S. government agencies — 43,297 — 43,297 State and municipal — 390,367 — 390,367 Mortgage-backed and asset-backed — 904,432 — 904,432 Corporate debt — — 9,925 9,925 Total available-for-sale securities — 1,338,096 9,925 1,348,021 Interest rate swap agreements — 9,183 — 9,183 Total assets $ — $ 1,425,573 $ 9,925 $ 1,435,498 Liabilities Interest rate swap agreements $ — $ (9,183) $ — $ (9,183) Total liabilities $ — $ (9,183) $ — $ (9,183) (1) The outstanding principal balance for residential loans held for sale as of December 31, 2020 was $75.5 million. 2019 (In thousands) Quoted Prices in Significant Other Significant Total Assets Residential mortgage loans held for sale (1) $ — $ 53,701 $ — $ 53,701 Investments available-for-sale: U.S. government agencies — 258,495 — 258,495 State and municipal — 233,649 — 233,649 Mortgage-backed and asset-backed — 570,759 — 570,759 Corporate debt — — 9,552 9,552 Trust preferred — — 310 310 Total debt securities — 1,062,903 9,862 1,072,765 Marketable equity securities — 568 — 568 Total available-for-sale securities — 1,063,471 9,862 1,073,333 Interest rate swap agreements — 2,507 — 2,507 Total assets $ — $ 1,119,679 $ 9,862 $ 1,129,541 Liabilities Interest rate swap agreements $ — $ (2,507) $ — $ (2,507) Total liabilities $ — $ (2,507) $ — $ (2,507) (1) The outstanding principal balance for residential loans held for sale as of December 31, 2019 was $52.6 million.
Activity of assets reported as Level 3	The following table provides activity of assets reported as Level 3 for the period indicated: Significant Unobservable Inputs (In thousands) (Level 3) Investments available-for-sale: Balance at January 1, 2020 $ 9,862 Transfer into Level 3 assets — Additions of Level 3 assets 3,050 Elimination of investments in WashingtonFirst and Revere sub debt (3,000) Sales of Level 3 assets (310) Total unrealized gains included in accumulated other comprehensive income 323 Balance at December 31, 2020 $ 9,925
Assets Measured at Fair Value on Nonrecurring Basis	The following tables set forth the Company’s financial assets subject to fair value adjustments on a non-recurring basis at December 31 for the year indicated that are valued at the lower of cost or market. Assets are classified in their entirety based on the lowest level of input that is significant to the fair value measurement: 2020 (In thousands) Quoted Prices in Significant Other Significant Total Total Losses Loans (1) $ — $ — $ 13,901 $ 13,901 $ (11,326) Other real estate owned — — 1,455 1,455 (286) Total $ — $ — $ 15,356 $ 15,356 $ (11,612) (1) Amounts represent the fair value of collateral for collateral dependent non-accrual loans allocated to the allowance for credit losses. Fair values are determined using actual market prices (Level 2), independent third party valuations and borrower records, discounted as appropriate (Level 3). 2019 (In thousands) Quoted Prices in Significant Other Significant Total Total Losses Loans (1) $ — $ — $ 6,886 $ 6,886 $ (6,299) Other real estate owned — — 1,482 1,482 (281) Total $ — $ — $ 8,368 $ 8,368 $ (6,580) (1) Amounts represent the fair value of collateral for collateral dependent non-accrual loans allocated to the allowance for credit losses. Fair values are determined using actual market prices (Level 2), independent third party valuations and borrower records, discounted as appropriate (Level 3).
Carrying Amounts And Fair Values of Company's Financial Instruments	The carrying amounts and fair values of the Company’s financial instruments at December 31 for the year indicated are presented in the following table: Fair Value Measurements 2020 Quoted Prices in Significant Other Significant (In thousands) Carrying Estimated Financial assets: Cash and cash equivalents $ 297,003 $ 297,003 $ 297,003 $ — $ — Residential mortgage loans held for sale 78,294 78,294 — 78,294 — Investments available-for-sale 1,348,021 1,348,021 — 1,338,096 9,925 Equity securities 65,760 65,760 65,760 — — Loans, net of allowance 10,235,142 10,336,355 — — 10,336,355 Interest rate swap agreements 9,183 9,183 — 9,183 — Accrued interest receivable 46,431 46,431 46,431 — — Bank owned life insurance 126,887 126,887 — 126,887 — Financial liabilities: Time deposits $ 1,657,662 $ 1,674,112 $ — $ 1,674,112 $ — Other deposits 8,375,407 8,375,407 8,375,407 — — Securities sold under retail repurchase agreements and federal funds purchased 543,157 543,157 — 543,157 — Advances from FHLB 379,075 390,593 — 390,593 — Subordinated debt 227,088 227,512 — — 227,512 Interest rate swap agreements 9,183 9,183 — 9,183 — Accrued interest payable 3,254 3,254 3,254 — — Fair Value Measurements 2019 Quoted Prices in Significant Other Significant (In thousands) Carrying Estimated Financial assets: Cash and cash equivalents $ 146,103 $ 146,103 $ 146,103 $ — $ — Residential mortgage loans held for sale 53,701 53,701 — 53,701 — Investments available-for-sale 1,073,333 1,073,333 — 1,063,471 9,862 Equity securities 51,803 51,803 51,803 — — Loans, net of allowance 6,649,100 6,628,054 — — 6,628,054 Interest rate swap agreements 2,507 2,507 — 2,507 — Accrued interest receivable 23,282 23,282 23,282 — — Bank owned life insurance 113,171 113,171 — 113,171 — Financial liabilities: Time deposits $ 1,542,322 $ 1,547,116 $ — $ 1,547,116 $ — Other deposits 4,897,997 4,897,997 4,897,997 — — Securities sold under retail repurchase agreements and federal funds purchased 213,605 213,605 — 213,605 — Advances from FHLB 513,777 520,729 — 520,729 — Subordinated debt 209,406 200,864 — — 200,864 Interest rate swap agreements 2,507 2,507 — 2,507 — Accrued interest payable 4,194 4,194 4,194 — —

PARENT COMPANY FINANCIAL INFO_2

PARENT COMPANY FINANCIAL INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Disclosure [Abstract]
Statements of Condition	Financial statements for Sandy Spring Bancorp, Inc. (Parent Only) for the periods indicated are presented in the following tables: Statements of Condition December 31, (In thousands) 2020 2019 Assets: Cash and cash equivalents $ 63,943 $ 90,361 Investments available-for-sale (at fair value) 9,925 10,430 Equity securities 568 — Investment in subsidiary 1,589,483 1,242,229 Goodwill 1,292 1,292 Other assets 2,684 1,480 Total assets $ 1,667,895 $ 1,345,792 Liabilities: Subordinated debt $ 196,454 $ 209,406 Accrued expenses and other liabilities 1,486 3,412 Total liabilities 197,940 212,818 Stockholders’ Equity: Common stock 47,057 34,970 Additional paid in capital 846,922 586,622 Retained earnings 557,271 515,714 Accumulated other comprehensive income/ (loss) 18,705 (4,332) Total stockholders’ equity 1,469,955 1,132,974 Total liabilities and stockholders’ equity $ 1,667,895 $ 1,345,792
Statements of Income/(Loss)	Statements of Income Year Ended December 31, (In thousands) 2020 2019 2018 Income: Cash dividends from subsidiary $ 74,410 $ 42,625 $ 39,370 Other income 932 1,093 897 Total income 75,342 43,718 40,267 Expenses: Interest 9,028 3,141 1,922 Other expenses 1,505 1,507 1,135 Total expenses 10,533 4,648 3,057 Income before income taxes and equity in undistributed income of subsidiary 64,809 39,070 37,210 Income benefit (1,988) (734) (283) Income before equity in undistributed income of subsidiary 66,797 39,804 37,493 Equity in undistributed income of subsidiary 30,156 76,629 63,371 Net income $ 96,953 $ 116,433 $ 100,864
Statements of Cash Flows	Statements of Cash Flows Year Ended December 31, (In thousands) 2020 2019 2018 Cash Flows from Operating Activities: Net income $ 96,953 $ 116,433 $ 100,864 Adjustments to reconcile net income to net cash provided by operating activities: Equity in undistributed income-subsidiary (30,156) (76,629) (63,371) Share based compensation expense 3,850 3,042 2,645 Tax benefit from stock options exercised 5 7 8 Other-net (9,732) — (3,252) Net cash provided by/ (used in) operating activities 60,920 42,853 36,894 Cash Flows from Investing Activities: Proceeds from sales of investment available-for-sale 310 — — Investment in subsidiary — (85,000) — Acquisition of business activity, net of cash paid — — 11,845 Net cash provided by/ (used in) investing activities 310 (85,000) 11,845 Cash Flows from Financing Activities: Retirement of subordinated debt (10,310) — — Proceeds from issuance of subordinated debt — 175,000 — Proceeds from issuance of common stock 1,997 1,433 1,395 Stock tendered for payment of withholding taxes (458) (703) (760) Repurchase of common stock (25,702) (24,284) — Dividends paid (53,175) (42,272) (39,277) Net cash provided by/ (used in) financing activities (87,648) 109,174 (38,642) Net increase/ (decrease) in cash and cash equivalents (26,418) 67,027 10,097 Cash and cash equivalents at beginning of year 90,361 23,334 13,237 Cash and cash equivalents at end of year $ 63,943 $ 90,361 $ 23,334

REGULATORY MATTERS (Tables)

REGULATORY MATTERS (Tables)	12 Months Ended
	Dec. 31, 2020
Banking and Thrift [Abstract]
Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations	The Company's and the Bank's actual capital amounts and ratios at December 31 for the years indicated are presented in the following table: Actual For Capital To be Well (Dollars in thousands) Amount Ratio Amount Ratio Amount Ratio As of December 31, 2020 Tier 1 Leverage: Company $ 1,078,213 8.92 % $ 483,619 4.00 % N/A N/A Sandy Spring Bank $ 1,199,570 9.93 % $ 483,175 4.00 % $ 603,969 5.00 % Common Equity Tier 1 Capital to risk- weighted assets: Company $ 1,078,213 10.58 % $ 458,612 4.50 % N/A N/A Sandy Spring Bank $ 1,199,570 11.79 % $ 457,920 4.50 % $ 661,441 6.50 % Tier 1 Capital to risk-weighted assets: Company $ 1,078,213 10.58 % $ 611,483 6.00 % N/A N/A Sandy Spring Bank $ 1,199,570 11.79 % $ 610,561 6.00 % $ 814,081 8.00 % Total Capital to risk-weighted assets: Company $ 1,419,973 13.93 % $ 815,311 8.00 % N/A N/A Sandy Spring Bank $ 1,347,102 13.24 % $ 814,081 8.00 % $ 1,017,601 10.00 % As of December 31, 2019 Tier 1 Leverage: Company $ 794,300 9.70 % $ 327,577 4.00 % N/A N/A Sandy Spring Bank $ 894,659 10.94 % $ 327,123 4.00 % $ 408,904 5.00 % Common Equity Tier 1 Capital to risk- weighted assets: Company $ 783,903 11.06 % $ 318,860 4.50 % N/A N/A Sandy Spring Bank $ 894,659 12.65 % $ 318,259 4.50 % $ 459,708 6.50 % Tier 1 Capital to risk-weighted assets: Company $ 794,300 11.21 % $ 425,147 6.00 % N/A N/A Sandy Spring Bank $ 894,659 12.65 % $ 424,346 6.00 % $ 565,794 8.00 % Total Capital to risk-weighted assets: Company $ 1,052,328 14.85 % $ 566,863 8.00 % N/A N/A Sandy Spring Bank $ 950,793 13.44 % $ 565,794 8.00 % $ 707,243 10.00 %

SEGMENT REPORTING (Tables)

SEGMENT REPORTING (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Operating Segments and Reconciliation of Information to Consolidated Financial Statements	Information for the operating segments and reconciliation of the information to the consolidated financial statements for the years ended December 31 is presented in the following tables: 2020 Community Investment Inter-Segment Interest income $ 423,560 $ 6 $ 7 $ (13) $ 423,560 Interest expense 60,414 — — (13) 60,401 Provision for credit losses 85,669 — — — 85,669 Non-interest income 78,940 6,810 17,831 (865) 102,716 Non-interest expenses 237,910 5,686 13,051 (865) 255,782 Income before income taxes 118,507 1,130 4,787 — 124,424 Income tax expense 25,907 313 1,251 — 27,471 Net income $ 92,600 $ 817 $ 3,536 $ — $ 96,953 Assets $ 12,800,537 $ 11,335 $ 57,768 $ (71,211) $ 12,798,429 2019 (In thousands) Community Investment Inter-Segment Interest income $ 347,867 $ 26 $ 13 $ (37) $ 347,869 Interest expense 82,598 — — (37) 82,561 Provision for credit losses 4,684 — — — 4,684 Non-interest income 55,042 6,621 10,326 (667) 71,322 Non-interest expenses 166,802 5,731 7,219 (667) 179,085 Income before income taxes 148,825 916 3,120 — 152,861 Income tax expense 35,350 258 820 — 36,428 Net income $ 113,475 $ 658 $ 2,300 $ — $ 116,433 Assets $ 8,624,590 $ 10,340 $ 16,424 $ (22,352) $ 8,629,002 2018 Community Investment Inter-Segment Interest income $ 324,081 $ 3 $ 8 $ (10) $ 324,082 Interest expense 63,647 — — (10) 63,637 Provision for credit losses 9,023 — — — 9,023 Non-interest income 45,841 6,153 9,670 (615) 61,049 Non-interest expenses 168,261 5,601 6,536 (615) 179,783 Income before income taxes 128,991 555 3,142 — 132,688 Income tax expense 30,827 169 828 — 31,824 Net income $ 98,164 $ 386 $ 2,314 $ — $ 100,864 Assets $ 8,246,282 $ 9,165 $ 16,332 $ (28,507) $ 8,243,272

QUARTERLY FINANCIAL RESULTS (_2

QUARTERLY FINANCIAL RESULTS (UNAUDITED) (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Consolidated Quarterly Financial Data	2020 (In thousands, except per share data) First Second Third Fourth Interest income $ 83,858 $ 114,927 $ 112,984 $ 111,791 Interest expense 19,524 13,413 15,500 11,964 Net interest income 64,334 101,514 97,484 99,827 Provision/ (credit) for credit losses 24,469 58,686 7,003 (4,489) Non-interest income 18,168 22,924 29,390 32,234 Non-interest expense 47,746 85,438 60,937 61,661 Income before income taxes 10,287 (19,686) 58,934 74,889 Income tax expense/ (benefit) 300 (5,348) 14,292 18,227 Net income/ (loss) $ 9,987 $ (14,338) $ 44,642 $ 56,662 Basic net income/ (loss) per common share $ 0.29 $ (0.31) $ 0.94 $ 1.19 Diluted net income/ (loss) per common share $ 0.28 $ (0.31) $ 0.94 $ 1.19 2019 (In thousands, except per share data) First Second Third Fourth Interest income $ 88,183 $ 87,214 $ 87,082 $ 85,390 Interest expense 21,433 21,029 20,292 19,807 Net interest income 66,750 66,185 66,790 65,583 Provision/ (credit) for loan losses (128) 1,633 1,524 1,655 Non-interest income 16,969 16,556 18,573 19,224 Non-interest expense 44,192 43,887 44,925 46,081 Income before income taxes 39,655 37,221 38,914 37,071 Income tax expense 9,338 8,945 9,531 8,614 Net income $ 30,317 $ 28,276 $ 29,383 $ 28,457 Basic net income per common share $ 0.85 $ 0.79 $ 0.82 $ 0.80 Diluted net income per common share $ 0.85 $ 0.79 $ 0.82 $ 0.80

SIGNIFICANT ACCOUNTING POLICI_3

SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Mar. 31, 2020
Property, Plant and Equipment [Line Items]
Allowance for credit loss		$ 2.8
Accounts receivable, after allowance for credit loss		$ 2.2
Maximum
Property, Plant and Equipment [Line Items]
Finite-lived intangible asset, useful life	15 years
Furniture and Fixtures | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Furniture and Fixtures | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	10 years
Computer Equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Computer Equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Building and Building Improvements | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	10 years
Building and Building Improvements | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	40 years

ACQUISITION OF REVERE BANK - Na

ACQUISITION OF REVERE BANK - Narrative (Details) $ / shares in Units, $ in Thousands	Mar. 31, 2020USD ($)bank	Dec. 31, 2020USD ($)$ / shares	Apr. 01, 2020USD ($)$ / sharesshares
Business Acquisition [Line Items]
Closing price (in dollars per share) | $ / shares		$ 22.64
Consideration transferred		$ 293,002
Assets acquired		2,846,356
Provisional amount of goodwill recognized		$ 515	$ 800
Sandy Spring Shareholders
Business Acquisition [Line Items]
Percentage of ownership in combined company			74.00%
Revere shareholders
Business Acquisition [Line Items]
Percentage of ownership in combined company			26.00%
Maryland-based Revere
Business Acquisition [Line Items]
Business acquisition rate of share exchange (in shares) | shares			1.05
Closing price (in dollars per share) | $ / shares			$ 22.64
Consideration transferred	$ 293,000
Assets acquired	$ 2,800,000
Number of banking offices | bank	11

ACQUISITION OF REVERE BANK - Pr

ACQUISITION OF REVERE BANK - Provisional fair values of acquired identifiable assets and liabilities assumed (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018	Apr. 01, 2020
Purchase price:
Fair value of common shares issued (12,768,949 shares) based on Sandy Spring's share price of $22.64	$ 289,089	$ 446,640
Fair value of Revere stock options converted to Sandy Spring stock options	3,611
Cash paid for cashed-out Revere stock options	291
Cash for fractional shares	11
Total purchase price	293,002
Identifiable assets:
Cash and cash equivalents	80,744
Investments available-for-sale	180,752
Loans	2,502,244
Premises and equipment	3,443
Accrued interest receivable	7,651
Core deposit intangible asset	18,360
Other assets	53,162
Total identifiable assets	2,846,356
Identifiable liabilities:
Deposits	2,322,422
Borrowings	205,514
Other liabilities	25,933
Total identifiable liabilities	2,553,869
Provisional fair value of net assets acquired including identifiable intangible assets	292,487
Provisional resulting goodwill	$ 515		$ 800
Stock repurchased and retired (in shares)	12,768,949	11,446,197
Closing price (in dollars per share)	$ 22.64

CASH AND DUE FROM BANKS (Narrat

CASH AND DUE FROM BANKS (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Abstract]
Compensating balance	$ 236.3	$ 105.3

INVESTMENTS - Amortized Cost an

INVESTMENTS - Amortized Cost and Estimated Fair Values of Investments Available-for-sale (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	$ 1,348,021	$ 1,073,333
Available-for-Sale Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,310,159	1,067,954
Gross Unrealized Gains	38,922	8,984
Gross Unrealized Losses	(1,060)	(3,605)
Estimated Fair Value	1,348,021	1,073,333
Available-for-Sale Securities | U.S. treasuries and government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	42,750	260,294
Gross Unrealized Gains	549	887
Gross Unrealized Losses	(2)	(2,686)
Estimated Fair Value	43,297	258,495
Available-for-Sale Securities | State and municipal
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	377,108	229,309
Gross Unrealized Gains	13,470	4,377
Gross Unrealized Losses	(211)	(37)
Estimated Fair Value	390,367	233,649
Available-for-Sale Securities | Mortgage-backed and asset-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	881,201	568,373
Gross Unrealized Gains	24,078	3,268
Gross Unrealized Losses	(847)	(882)
Estimated Fair Value	904,432	570,759
Available-for-Sale Securities | Corporate debt
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	9,100	9,100
Gross Unrealized Gains	825	452
Gross Unrealized Losses	0	0
Estimated Fair Value	9,925	9,552
Available-for-Sale Securities | Trust preferred
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	0	310
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	0	310
Available-for-Sale Securities | Debt Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,310,159	1,067,386
Gross Unrealized Gains	38,922	8,984
Gross Unrealized Losses	(1,060)	(3,605)
Estimated Fair Value	1,348,021	1,072,765
Available-for-Sale Securities | Marketable equity securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	0	568
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 0	$ 568

INVESTMENTS - Narrative (Detail

INVESTMENTS - Narrative (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Schedule of Investments [Line Items]
Investments available-for-sale book value	$ 465.7	$ 424.8
Government National Mortgage Association Certificates And Obligations Federal National Mortgage Association Certificates And Obligations And Federal Home Loan Mortgage Corporation Certificates And Obligations | Collateralized Mortgage Obligations
Schedule of Investments [Line Items]
Mortgage-backed securities	318.6
Government National Mortgage Association Certificates And Obligations Federal National Mortgage Association Certificates And Obligations And Federal Home Loan Mortgage Corporation Certificates And Obligations | Mortgage-backed and asset-backed
Schedule of Investments [Line Items]
Mortgage-backed securities	520.1
Government National Mortgage Association Certificates And Obligations Federal National Mortgage Association Certificates And Obligations And Federal Home Loan Mortgage Corporation Certificates And Obligations | SBA asset backed securities
Schedule of Investments [Line Items]
Mortgage-backed securities	$ 65.7

INVESTMENTS - Gross Unrealized

INVESTMENTS - Gross Unrealized Losses and Fair Value by Length of Time of Available-For-Sale Securities (Detail) $ in Thousands	Dec. 31, 2020USD ($)security	Dec. 31, 2019USD ($)security
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	34	50
Fair Value
Less Than 12 Months	$ 92,868	$ 248,365
12 Months or More	76,879	94,778
Total	169,747	343,143
Unrealized Losses
Less Than 12 Months	367	2,756
12 Months or More	693	849
Total	$ 1,060	$ 3,605
U.S. treasuries and government agencies
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	2	12
Fair Value
Less Than 12 Months	$ 25,369	$ 133,221
12 Months or More	0	17,911
Total	25,369	151,132
Unrealized Losses
Less Than 12 Months	2	2,211
12 Months or More	0	475
Total	$ 2	$ 2,686
State and municipal
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	8	3
Fair Value
Less Than 12 Months	$ 22,753	$ 7,227
12 Months or More	0	0
Total	22,753	7,227
Unrealized Losses
Less Than 12 Months	211	37
12 Months or More	0	0
Total	$ 211	$ 37
Mortgage-backed and asset-backed
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	24	35
Fair Value
Less Than 12 Months	$ 44,746	$ 107,917
12 Months or More	76,879	76,867
Total	121,625	184,784
Unrealized Losses
Less Than 12 Months	154	508
12 Months or More	693	374
Total	$ 847	$ 882

INVESTMENTS - Estimated fair va

INVESTMENTS - Estimated fair values and amortized costs of debt securities available-for-sale by contractual maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value
Total available-for-sale debt securities	$ 1,348,021	$ 1,072,765
Amortized Cost
Total available-for-sale debt securities	1,310,159	1,067,386
U.S. treasuries and government agencies
Fair Value
One year or less	33,963	69,799
One to five years	9,334	96,709
Five to ten years	0	0
After ten years	0	91,987
Amortized Cost
One year or less	33,833	69,330
One to five years	8,917	96,507
Five to ten years	0	0
After ten years	0	94,457
State and municipal
Fair Value
One year or less	16,581	33,311
One to five years	44,910	76,723
Five to ten years	59,059	75,820
After ten years	269,817	47,795
Amortized Cost
One year or less	16,458	33,054
One to five years	43,857	75,432
Five to ten years	56,130	73,741
After ten years	260,663	47,082
Mortgage-backed and asset-backed
Fair Value
One year or less	1	852
One to five years	21,637	7,125
Five to ten years	74,142	55,226
After ten years	808,652	507,556
Amortized Cost
One year or less	1	822
One to five years	21,229	6,969
Five to ten years	72,481	54,799
After ten years	787,490	505,783
Corporate debt
Fair Value
One year or less	0	0
One to five years	2,318	0
Five to ten years	7,607	9,552
After ten years	0	0
Amortized Cost
One year or less	0	0
One to five years	2,100	0
Five to ten years	7,000	9,100
After ten years	0	0
Trust preferred
Fair Value
One year or less	0	0
One to five years	0	0
Five to ten years	0	0
After ten years	0	310
Amortized Cost
One year or less	0	0
One to five years	0	0
Five to ten years	0	0
After ten years	$ 0	$ 310

INVESTMENTS - Other Equity Secu

INVESTMENTS - Other Equity Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Federal Home Loan Bank Stock and Federal Reserve Bank Stock [Abstract]
Federal Reserve Bank stock	$ 38,650	$ 22,559
Federal Home Loan Bank of Atlanta stock	26,433	29,244
Other equity securities	677	0
Total equity securities	$ 65,760	$ 51,803

INVESTMENTS - Gross Realized Ga

INVESTMENTS - Gross Realized Gains and Losses on All Investments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Gross realized gains from sales of investments available-for-sale	$ 1,297	$ 14	$ 2,519
Gross realized losses from sales of investments available-for-sale	(1,068)	(2)	(2,343)
Net gains from calls of investments available-for-sale	238	65	14
Net investment securities gains	$ 467	$ 77	$ 190

LOANS - Narrative (Detail)

LOANS - Narrative (Detail) - USD ($) $ in Thousands	Apr. 01, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Loans and Leases Receivable Disclosure [Line Items]
Unearned income and deferred fees		$ 24,500	$ 1,800
Loans receivable with a gross amortized cost basis	$ 2,500,000
PCD Loans acquired	974,800
Initial allowance on Revere PCD loans	18,600	18,628	$ 0	$ 0
Fair value premium	4,500
Total fair value of PCD loans as of the acquisition date	960,700	911,400
PCD remaining unamortized fair value premium		4,000
PCD loans non-accruing at the time of acquisition	11,300
Non-PCD loans	1,500,000	1,300,000
Net fair value premium	$ 2,100
Non-PCD remaining unamortized fair value premium		1,400
Paycheck Protection Program
Loans and Leases Receivable Disclosure [Line Items]
Unearned income and deferred fees		$ 21,200

LOANS - Loan Portfolio Segment

LOANS - Loan Portfolio Segment Balances (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 10,400,509	$ 6,705,232
Commercial investor real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	3,634,720
Commercial owner-occupied real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,642,216
Commercial AD&C
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,050,973
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,105,179
Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	182,619
Commercial real estate: | Commercial investor real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	3,634,720	2,169,156
Commercial real estate: | Commercial owner-occupied real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,642,216	1,288,677
Commercial real estate: | Commercial AD&C
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,050,973	684,010
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	8,595,457	4,942,862
Commercial | Commercial business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,267,548	801,019
Residential real estate: | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,105,179	1,149,327
Residential real estate: | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	182,619	146,279
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	517,254	466,764
Total residential and consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 1,805,052	$ 1,762,370

LOANS - Summary of Changes In A

LOANS - Summary of Changes In Amounts Of Loans Outstanding (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Balance at beginning of period	$ 51,367	$ 54,208	$ 36,712
Additions	46,846	4,737	21,871
Repayments	(2,208)	(7,578)	(4,375)
Balance at end of period	$ 96,005	$ 51,367	$ 54,208

CREDIT QUALITY ASSESSMENT - All

CREDIT QUALITY ASSESSMENT - Allowance for credit loss activity (Detail) - USD ($) $ in Thousands	Apr. 01, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		$ 56,132	$ 53,486	$ 45,257
Initial allowance on Revere PCD loans	$ 18,600	18,628	0	0
Provision for credit losses		85,669	4,684	9,023
Loan charge-offs		(1,819)	(2,668)	(1,416)
Loan recoveries		1,012	630	622
Net charge-offs		(807)	(2,038)	(794)
Balance at period end		165,367	56,132	53,486
Initial allowance on PCD loans at adoption of ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		2,762	0	0
Balance at period end			2,762	0
Transition impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		$ 2,983	0	0
Balance at period end			$ 2,983	$ 0

CREDIT QUALITY ASSESSMENT - Col

CREDIT QUALITY ASSESSMENT - Collateral Dependent Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Credit Loss [Abstract]
Collateral dependent loans individually evaluated for credit loss with an allowance	$ 20,717	$ 15,333
Collateral dependent loans individually evaluated for credit loss without an allowance	77,001	9,440
Total individually evaluated collateral dependent loans	97,718	24,773
Allowance for credit losses related to loans evaluated individually	11,405	5,501
Allowance for credit losses related to loans evaluated collectively	153,962	50,631
Total allowance for credit losses	$ 165,367	$ 56,132	$ 53,486	$ 45,257

CREDIT QUALITY ASSESSMENT - A_2

CREDIT QUALITY ASSESSMENT - Allowance for Credit or Loan Losses by Respective Loan Portfolio Segment (Detail) - USD ($) $ in Thousands	Apr. 01, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		$ 56,132	$ 53,486	$ 45,257
Initial allowance on Revere PCD loans	$ 18,600	18,628	0	0
Provision		85,669	4,684	9,023
Charge-offs		(1,819)	(2,668)	(1,416)
Recoveries		1,012	630	622
Net (charge-offs)/ recoveries		(807)	(2,038)	(794)
Balance at period end		165,367	56,132	53,486
Total loans		$ 10,400,509	$ 6,705,232
Allowance for credit losses to total loans ratio		1.59%	0.84%
Balance of loans individually evaluated for credit loss		$ 97,718	$ 24,773
Allowance related to loans evaluated individually		$ 11,405	5,501
Individual allowance to loans evaluated individually ratio		11.67%
Balance of loans collectively evaluated for credit loss		$ 10,302,791
Allowance related to loans evaluated collectively		$ 153,962	50,631
Balance of loans specifically evaluated for impairment			24,773
Allowance for loans specifically evaluated for impairment			$ 5,501
Specific allowance to specific loans ratio			22.21%
Balance of loans collectively evaluated			$ 6,667,375
Allowance for loans collectively evaluated			$ 50,631
Collective allowance to loans evaluated collectively ratio		1.49%	0.76%
Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance of loans acquired with deteriorated credit quality			$ 13,084
Allowance for loans acquired with deteriorated credit quality			$ 0
Allowance to loan acquired with deteriorated credit quality ratio			0.00%
Initial allowance on PCD loans at adoption of ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		$ 2,762	$ 0	0
Balance at period end			2,762	0
Transition impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		2,983	0	0
Balance at period end			2,983	0
Commercial investor real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Total loans		3,634,720
Commercial owner-occupied real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Total loans		1,642,216
Commercial AD&C
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Total loans		1,050,973
Residential mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Total loans		1,105,179
Residential construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Total loans		182,619
Commercial real estate: | Commercial investor real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		18,407	17,603
Initial allowance on Revere PCD loans		7,973
Provision		33,431	788
Charge-offs		(411)	0
Recoveries		15	16
Net (charge-offs)/ recoveries		(396)	16
Balance at period end		57,404	18,407	17,603
Total loans		$ 3,634,720	$ 2,169,156
Allowance for credit losses to total loans ratio		1.58%	0.85%
Balance of loans individually evaluated for credit loss		$ 45,227
Allowance related to loans evaluated individually		$ 1,273
Individual allowance to loans evaluated individually ratio		2.81%
Balance of loans collectively evaluated for credit loss		$ 3,589,493
Allowance related to loans evaluated collectively		$ 56,131
Balance of loans specifically evaluated for impairment			$ 9,212
Allowance for loans specifically evaluated for impairment			$ 1,529
Specific allowance to specific loans ratio			16.60%
Balance of loans collectively evaluated			$ 2,150,400
Allowance for loans collectively evaluated			$ 16,878
Collective allowance to loans evaluated collectively ratio		1.56%	0.78%
Commercial real estate: | Commercial investor real estate | Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance of loans acquired with deteriorated credit quality			$ 9,544
Allowance for loans acquired with deteriorated credit quality			$ 0
Allowance to loan acquired with deteriorated credit quality ratio			0.00%
Commercial real estate: | Commercial investor real estate | Initial allowance on PCD loans at adoption of ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		$ 1,114
Balance at period end			$ 1,114
Commercial real estate: | Commercial investor real estate | Transition impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		(3,125)
Balance at period end			(3,125)
Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		6,884	6,307
Initial allowance on Revere PCD loans		2,782
Provision		10,008	577
Charge-offs		0	0
Recoveries		0	0
Net (charge-offs)/ recoveries		0	0
Balance at period end		20,061	6,884	6,307
Total loans		$ 1,642,216	$ 1,288,677
Allowance for credit losses to total loans ratio		1.22%	0.53%
Balance of loans individually evaluated for credit loss		$ 11,561
Allowance related to loans evaluated individually		$ 0
Individual allowance to loans evaluated individually ratio		0.00%
Balance of loans collectively evaluated for credit loss		$ 1,630,655
Allowance related to loans evaluated collectively		$ 20,061
Balance of loans specifically evaluated for impairment			$ 4,148
Allowance for loans specifically evaluated for impairment			$ 23
Specific allowance to specific loans ratio			0.55%
Balance of loans collectively evaluated			$ 1,284,529
Allowance for loans collectively evaluated			$ 6,861
Collective allowance to loans evaluated collectively ratio		1.23%	0.53%
Commercial real estate: | Commercial owner-occupied real estate | Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance of loans acquired with deteriorated credit quality			$ 0
Allowance for loans acquired with deteriorated credit quality			$ 0
Allowance to loan acquired with deteriorated credit quality ratio			0.00%
Commercial real estate: | Commercial owner-occupied real estate | Initial allowance on PCD loans at adoption of ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		$ 0
Balance at period end			$ 0
Commercial real estate: | Commercial owner-occupied real estate | Transition impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		387
Balance at period end			387
Commercial real estate: | Commercial AD&C
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		7,590	5,944
Initial allowance on Revere PCD loans		1,248
Provision		10,743	1,418
Charge-offs		0	0
Recoveries		0	228
Net (charge-offs)/ recoveries		0	228
Balance at period end		22,157	7,590	5,944
Total loans		$ 1,050,973	$ 684,010
Allowance for credit losses to total loans ratio		2.11%	1.11%
Balance of loans individually evaluated for credit loss		$ 15,044
Allowance related to loans evaluated individually		$ 603
Individual allowance to loans evaluated individually ratio		4.01%
Balance of loans collectively evaluated for credit loss		$ 1,035,929
Allowance related to loans evaluated collectively		$ 21,554
Balance of loans specifically evaluated for impairment			$ 829
Allowance for loans specifically evaluated for impairment			$ 132
Specific allowance to specific loans ratio			15.92%
Balance of loans collectively evaluated			$ 683,181
Allowance for loans collectively evaluated			$ 7,458
Collective allowance to loans evaluated collectively ratio		2.08%	1.09%
Commercial real estate: | Commercial AD&C | Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance of loans acquired with deteriorated credit quality			$ 0
Allowance for loans acquired with deteriorated credit quality			$ 0
Allowance to loan acquired with deteriorated credit quality ratio			0.00%
Commercial real estate: | Commercial AD&C | Initial allowance on PCD loans at adoption of ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		$ 0
Balance at period end			$ 0
Commercial real estate: | Commercial AD&C | Transition impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		2,576
Balance at period end			2,576
Commercial Business
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Total loans		8,595,457	4,942,862
Balance of loans individually evaluated for credit loss		23,648
Allowance related to loans evaluated individually		9,529
Commercial Business | Commercial business
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		11,395	11,377
Initial allowance on Revere PCD loans		6,289
Provision		24,374	1,164
Charge-offs		(491)	(1,195)
Recoveries		702	49
Net (charge-offs)/ recoveries		211	(1,146)
Balance at period end		46,806	11,395	11,377
Total loans		$ 2,267,548	$ 801,019
Allowance for credit losses to total loans ratio		2.06%	1.42%
Balance of loans individually evaluated for credit loss		$ 23,648
Allowance related to loans evaluated individually		$ 9,529
Individual allowance to loans evaluated individually ratio		40.30%
Balance of loans collectively evaluated for credit loss		$ 2,243,900
Allowance related to loans evaluated collectively		$ 37,277
Balance of loans specifically evaluated for impairment			$ 8,867
Allowance for loans specifically evaluated for impairment			$ 3,817
Specific allowance to specific loans ratio			43.05%
Balance of loans collectively evaluated			$ 789,613
Allowance for loans collectively evaluated			$ 7,578
Collective allowance to loans evaluated collectively ratio		1.66%	0.96%
Commercial Business | Commercial business | Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance of loans acquired with deteriorated credit quality			$ 2,539
Allowance for loans acquired with deteriorated credit quality			$ 0
Allowance to loan acquired with deteriorated credit quality ratio			0.00%
Commercial Business | Commercial business | Initial allowance on PCD loans at adoption of ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		$ 1,549
Balance at period end			$ 1,549
Commercial Business | Commercial business | Transition impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		2,988
Balance at period end			2,988
Residential real estate: | Residential mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		8,803	8,881
Initial allowance on Revere PCD loans		243
Provision		3,016	474
Charge-offs		(484)	(690)
Recoveries		105	138
Net (charge-offs)/ recoveries		(379)	(552)
Balance at period end		11,295	8,803	8,881
Total loans		$ 1,105,179	$ 1,149,327
Allowance for credit losses to total loans ratio		1.02%	0.77%
Balance of loans individually evaluated for credit loss		$ 1,874
Allowance related to loans evaluated individually		$ 0
Individual allowance to loans evaluated individually ratio		0.00%
Balance of loans collectively evaluated for credit loss		$ 1,103,305
Allowance related to loans evaluated collectively		$ 11,295
Balance of loans specifically evaluated for impairment			$ 1,717
Allowance for loans specifically evaluated for impairment			$ 0
Specific allowance to specific loans ratio			0.00%
Balance of loans collectively evaluated			$ 1,147,602
Allowance for loans collectively evaluated			$ 8,803
Collective allowance to loans evaluated collectively ratio		1.02%	0.77%
Residential real estate: | Residential mortgage | Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance of loans acquired with deteriorated credit quality			$ 8
Allowance for loans acquired with deteriorated credit quality			$ 0
Allowance to loan acquired with deteriorated credit quality ratio			0.00%
Residential real estate: | Residential mortgage | Initial allowance on PCD loans at adoption of ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		$ 0
Balance at period end			$ 0
Residential real estate: | Residential mortgage | Transition impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		(388)
Balance at period end			(388)
Residential real estate: | Residential construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		967	1,261
Initial allowance on Revere PCD loans		6
Provision		798	(302)
Charge-offs		0	0
Recoveries		6	8
Net (charge-offs)/ recoveries		6	8
Balance at period end		1,502	967	1,261
Total loans		$ 182,619	$ 146,279
Allowance for credit losses to total loans ratio		0.82%	0.66%
Balance of loans individually evaluated for credit loss		$ 0
Allowance related to loans evaluated individually		$ 0
Individual allowance to loans evaluated individually ratio		0.00%
Balance of loans collectively evaluated for credit loss		$ 182,619
Allowance related to loans evaluated collectively		$ 1,502
Balance of loans specifically evaluated for impairment			$ 0
Allowance for loans specifically evaluated for impairment			$ 0
Specific allowance to specific loans ratio			0.00%
Balance of loans collectively evaluated			$ 146,279
Allowance for loans collectively evaluated			$ 967
Collective allowance to loans evaluated collectively ratio		0.82%	0.66%
Residential real estate: | Residential construction | Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance of loans acquired with deteriorated credit quality			$ 0
Allowance for loans acquired with deteriorated credit quality			$ 0
Allowance to loan acquired with deteriorated credit quality ratio			0.00%
Residential real estate: | Residential construction | Initial allowance on PCD loans at adoption of ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		$ 0
Balance at period end			$ 0
Residential real estate: | Residential construction | Transition impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		(275)
Balance at period end			(275)
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		2,086	2,113
Initial allowance on Revere PCD loans		87
Provision		3,299	565
Charge-offs		(433)	(783)
Recoveries		184	191
Net (charge-offs)/ recoveries		(249)	(592)
Balance at period end		6,142	2,086	$ 2,113
Total loans		$ 517,254	$ 466,764
Allowance for credit losses to total loans ratio		1.19%	0.45%
Balance of loans individually evaluated for credit loss		$ 364
Allowance related to loans evaluated individually		$ 0
Individual allowance to loans evaluated individually ratio		0.00%
Balance of loans collectively evaluated for credit loss		$ 516,890
Allowance related to loans evaluated collectively		$ 6,142
Balance of loans specifically evaluated for impairment			$ 0
Allowance for loans specifically evaluated for impairment			$ 0
Specific allowance to specific loans ratio			0.00%
Balance of loans collectively evaluated			$ 465,771
Allowance for loans collectively evaluated			$ 2,086
Collective allowance to loans evaluated collectively ratio		1.19%	0.45%
Consumer | Financial Asset Acquired with Credit Deterioration
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance of loans acquired with deteriorated credit quality			$ 993
Allowance for loans acquired with deteriorated credit quality			$ 0
Allowance to loan acquired with deteriorated credit quality ratio			0.00%
Consumer | Initial allowance on PCD loans at adoption of ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		$ 99
Balance at period end			$ 99
Consumer | Transition impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year		$ 820
Balance at period end			$ 820

CREDIT QUALITY ASSESSMENT - C_2

CREDIT QUALITY ASSESSMENT - Collateral dependent loans individually evaluated for credit loss (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	$ 20,717	$ 15,333
Allowance related to loans evaluated individually	11,405	5,501
Loans individually evaluated for credit loss without an allowance	77,001	9,440
Total individually evaluated collateral dependent loans	97,718	$ 24,773
Total unpaid contractual principal balance	115,816
Non-accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	17,419
Loans individually evaluated for credit loss without an allowance	71,764
Total individually evaluated collateral dependent loans	89,183
Non-accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	2,709
Loans individually evaluated for credit loss without an allowance	3,509
Total individually evaluated collateral dependent loans	6,218
Accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	589
Loans individually evaluated for credit loss without an allowance	1,728
Total individually evaluated collateral dependent loans	2,317
Commercial real estate: | Commercial investor real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	5,612
Allowance related to loans evaluated individually	1,273
Loans individually evaluated for credit loss without an allowance	39,615
Total individually evaluated collateral dependent loans	45,227
Total unpaid contractual principal balance	49,920
Commercial real estate: | Commercial investor real estate | Non-accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	4,913
Loans individually evaluated for credit loss without an allowance	39,615
Total individually evaluated collateral dependent loans	44,528
Commercial real estate: | Commercial investor real estate | Non-accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	699
Loans individually evaluated for credit loss without an allowance	0
Total individually evaluated collateral dependent loans	699
Commercial real estate: | Commercial investor real estate | Accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Loans individually evaluated for credit loss without an allowance	0
Total individually evaluated collateral dependent loans	0
Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Allowance related to loans evaluated individually	0
Loans individually evaluated for credit loss without an allowance	11,561
Total individually evaluated collateral dependent loans	11,561
Total unpaid contractual principal balance	15,309
Commercial real estate: | Commercial owner-occupied real estate | Non-accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Loans individually evaluated for credit loss without an allowance	9,315
Total individually evaluated collateral dependent loans	9,315
Commercial real estate: | Commercial owner-occupied real estate | Non-accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Loans individually evaluated for credit loss without an allowance	2,246
Total individually evaluated collateral dependent loans	2,246
Commercial real estate: | Commercial owner-occupied real estate | Accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Loans individually evaluated for credit loss without an allowance	0
Total individually evaluated collateral dependent loans	0
Commercial real estate: | Commercial AD&C
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	1,328
Allowance related to loans evaluated individually	603
Loans individually evaluated for credit loss without an allowance	13,716
Total individually evaluated collateral dependent loans	15,044
Total unpaid contractual principal balance	16,040
Commercial real estate: | Commercial AD&C | Non-accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	1,328
Loans individually evaluated for credit loss without an allowance	13,716
Total individually evaluated collateral dependent loans	15,044
Commercial real estate: | Commercial AD&C | Non-accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Loans individually evaluated for credit loss without an allowance	0
Total individually evaluated collateral dependent loans	0
Commercial real estate: | Commercial AD&C | Accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Loans individually evaluated for credit loss without an allowance	0
Total individually evaluated collateral dependent loans	0
Commercial Business
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	13,777
Allowance related to loans evaluated individually	9,529
Loans individually evaluated for credit loss without an allowance	9,871
Total individually evaluated collateral dependent loans	23,648
Total unpaid contractual principal balance	30,958
Commercial Business | Non-accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	11,178
Loans individually evaluated for credit loss without an allowance	9,118
Total individually evaluated collateral dependent loans	20,296
Commercial Business | Non-accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	2,010
Loans individually evaluated for credit loss without an allowance	627
Total individually evaluated collateral dependent loans	2,637
Commercial Business | Accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	589
Loans individually evaluated for credit loss without an allowance	126
Total individually evaluated collateral dependent loans	715
Residential real estate: | Residential mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Allowance related to loans evaluated individually	0
Loans individually evaluated for credit loss without an allowance	1,874
Total individually evaluated collateral dependent loans	1,874
Total unpaid contractual principal balance	3,225
Residential real estate: | Residential mortgage | Non-accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Loans individually evaluated for credit loss without an allowance	0
Total individually evaluated collateral dependent loans	0
Residential real estate: | Residential mortgage | Non-accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Loans individually evaluated for credit loss without an allowance	272
Total individually evaluated collateral dependent loans	272
Residential real estate: | Residential mortgage | Accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Loans individually evaluated for credit loss without an allowance	1,602
Total individually evaluated collateral dependent loans	1,602
Residential real estate: | Residential construction
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Allowance related to loans evaluated individually	0
Loans individually evaluated for credit loss without an allowance	0
Total individually evaluated collateral dependent loans	0
Total unpaid contractual principal balance	0
Residential real estate: | Residential construction | Non-accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Loans individually evaluated for credit loss without an allowance	0
Total individually evaluated collateral dependent loans	0
Residential real estate: | Residential construction | Non-accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Loans individually evaluated for credit loss without an allowance	0
Total individually evaluated collateral dependent loans	0
Residential real estate: | Residential construction | Accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Loans individually evaluated for credit loss without an allowance	0
Total individually evaluated collateral dependent loans	0
Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Allowance related to loans evaluated individually	0
Loans individually evaluated for credit loss without an allowance	364
Total individually evaluated collateral dependent loans	364
Total unpaid contractual principal balance	364
Consumer | Non-accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Loans individually evaluated for credit loss without an allowance	0
Total individually evaluated collateral dependent loans	0
Consumer | Non-accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Loans individually evaluated for credit loss without an allowance	364
Total individually evaluated collateral dependent loans	364
Consumer | Accruing | Restructured
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for credit loss with an allowance	0
Loans individually evaluated for credit loss without an allowance	0
Total individually evaluated collateral dependent loans	$ 0

CREDIT QUALITY ASSESSMENT - Non

CREDIT QUALITY ASSESSMENT - Non-accrual Loans (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Financing Receivable, Nonaccrual [Line Items]
Average non-accrual loans for the period	$ 72,562
Contractual interest income due on non-accrual loans during the period	18,301
Commercial real estate: | Commercial investor real estate
Financing Receivable, Nonaccrual [Line Items]
Average non-accrual loans for the period	26,849
Contractual interest income due on non-accrual loans during the period	6,547
Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Nonaccrual [Line Items]
Average non-accrual loans for the period	6,605
Contractual interest income due on non-accrual loans during the period	2,741
Commercial real estate: | Commercial AD&C
Financing Receivable, Nonaccrual [Line Items]
Average non-accrual loans for the period	4,267
Contractual interest income due on non-accrual loans during the period	4,505
Commercial Business
Financing Receivable, Nonaccrual [Line Items]
Average non-accrual loans for the period	16,532
Contractual interest income due on non-accrual loans during the period	2,858
Residential real estate: | Residential mortgage
Financing Receivable, Nonaccrual [Line Items]
Average non-accrual loans for the period	11,634
Contractual interest income due on non-accrual loans during the period	918
Residential real estate: | Residential construction
Financing Receivable, Nonaccrual [Line Items]
Average non-accrual loans for the period	0
Contractual interest income due on non-accrual loans during the period	0
Consumer
Financing Receivable, Nonaccrual [Line Items]
Average non-accrual loans for the period	6,675
Contractual interest income due on non-accrual loans during the period	$ 732

CREDIT QUALITY ASSESSMENT - Nar

CREDIT QUALITY ASSESSMENT - Narrative (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans placed on non-accrual	$ 85,300,000
Reversal of uncollected accrued interest	2,200,000
Specific allowance	1,020,000	$ 401,000
Other real estate owned	1,455,000	1,482,000
Consumer mortgage loan	0
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other real estate owned	300,000	64,000
Restructured loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructurings balance	8,500,000	7,900,000
Troubled debt restructurings restructured accruing	2,300,000	2,600,000
Troubled debt restructurings restructured non-accruing	6,200,000	5,300,000
Loans restructured during the period	4,500,000	2,400,000
Specific allowance	1,000,000	400,000
Other real estate owned	$ 1,500,000	$ 1,500,000

CREDIT QUALITY ASSESSMENT - Rec

CREDIT QUALITY ASSESSMENT - Recorded Investment with Respect to Impaired loans, Associated Allowance by Applicable Portfolio Segment (Detail) $ in Thousands	Dec. 31, 2019USD ($)
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	$ 15,333
Allowance	5,501
Impaired loans without a specific allowance:	9,440
Impaired loans	24,773
Unpaid principal balance in total impaired loans	34,620
Non-accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	12,652
Impaired loans without a specific allowance:	4,188
Impaired loans	16,840
Restructured | Accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	266
Impaired loans without a specific allowance:	2,370
Impaired loans	2,636
Restructured | Non-accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	2,415
Impaired loans without a specific allowance:	2,882
Impaired loans	5,297
All Other Loans
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	0
Allowance	0
Impaired loans without a specific allowance:	1,717
Impaired loans	1,717
Unpaid principal balance in total impaired loans	2,618
All Other Loans | Non-accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	0
Impaired loans without a specific allowance:	0
Impaired loans	0
All Other Loans | Restructured | Accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	0
Impaired loans without a specific allowance:	1,444
Impaired loans	1,444
All Other Loans | Restructured | Non-accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	0
Impaired loans without a specific allowance:	273
Impaired loans	273
Commercial real estate: | Commercial investor real estate
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	5,885
Allowance	1,529
Impaired loans without a specific allowance:	3,327
Impaired loans	9,212
Unpaid principal balance in total impaired loans	13,805
Commercial real estate: | Commercial investor real estate | Non-accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	5,448
Impaired loans without a specific allowance:	2,552
Impaired loans	8,000
Commercial real estate: | Commercial investor real estate | Restructured | Accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	0
Impaired loans without a specific allowance:	775
Impaired loans	775
Commercial real estate: | Commercial investor real estate | Restructured | Non-accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	437
Impaired loans without a specific allowance:	0
Impaired loans	437
Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	889
Allowance	23
Impaired loans without a specific allowance:	3,259
Impaired loans	4,148
Unpaid principal balance in total impaired loans	6,072
Commercial real estate: | Commercial owner-occupied real estate | Non-accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	767
Impaired loans without a specific allowance:	1,522
Impaired loans	2,289
Commercial real estate: | Commercial owner-occupied real estate | Restructured | Accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	0
Impaired loans without a specific allowance:	0
Impaired loans	0
Commercial real estate: | Commercial owner-occupied real estate | Restructured | Non-accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	122
Impaired loans without a specific allowance:	1,737
Impaired loans	1,859
Commercial real estate: | Commercial AD&C
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	829
Allowance	132
Impaired loans without a specific allowance:	0
Impaired loans	829
Unpaid principal balance in total impaired loans	829
Commercial real estate: | Commercial AD&C | Non-accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	829
Impaired loans without a specific allowance:	0
Impaired loans	829
Commercial real estate: | Commercial AD&C | Restructured | Accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	0
Impaired loans without a specific allowance:	0
Impaired loans	0
Commercial real estate: | Commercial AD&C | Restructured | Non-accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	0
Impaired loans without a specific allowance:	0
Impaired loans	0
Commercial Business
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	7,730
Allowance	3,817
Impaired loans without a specific allowance:	1,137
Impaired loans	8,867
Unpaid principal balance in total impaired loans	11,296
Commercial Business | Non-accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	5,608
Impaired loans without a specific allowance:	114
Impaired loans	5,722
Commercial Business | Restructured | Accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	266
Impaired loans without a specific allowance:	151
Impaired loans	417
Commercial Business | Restructured | Non-accruing
Financing Receivable, Impaired [Line Items]
Impaired loans with a specific allowance:	1,856
Impaired loans without a specific allowance:	872
Impaired loans	$ 2,728

CREDIT QUALITY ASSESSMENT - Imp

CREDIT QUALITY ASSESSMENT - Impaired Loans by Portfolio (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Financing Receivable, Impaired [Line Items]
Average impaired loans for the period	$ 23,365
Contractual interest income due on impaired loans during the period	1,947
Interest income on impaired loans recognized on a cash basis	465
Interest income on impaired loans recognized on an accrual basis	169
All Other Loans
Financing Receivable, Impaired [Line Items]
Average impaired loans for the period	1,577
Contractual interest income due on impaired loans during the period	128
Interest income on impaired loans recognized on a cash basis	8
Interest income on impaired loans recognized on an accrual basis	68
Commercial real estate: | Commercial investor real estate
Financing Receivable, Impaired [Line Items]
Average impaired loans for the period	7,565
Contractual interest income due on impaired loans during the period	786
Interest income on impaired loans recognized on a cash basis	49
Interest income on impaired loans recognized on an accrual basis	39
Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Impaired [Line Items]
Average impaired loans for the period	4,390
Contractual interest income due on impaired loans during the period	258
Interest income on impaired loans recognized on a cash basis	187
Interest income on impaired loans recognized on an accrual basis	0
Commercial real estate: | Commercial AD&C
Financing Receivable, Impaired [Line Items]
Average impaired loans for the period	2,052
Contractual interest income due on impaired loans during the period	127
Interest income on impaired loans recognized on a cash basis	0
Interest income on impaired loans recognized on an accrual basis	0
Commercial Business
Financing Receivable, Impaired [Line Items]
Average impaired loans for the period	7,781
Contractual interest income due on impaired loans during the period	648
Interest income on impaired loans recognized on a cash basis	221
Interest income on impaired loans recognized on an accrual basis	$ 62

CREDIT QUALITY ASSESSMENT - Inf

CREDIT QUALITY ASSESSMENT - Information on the credit quality of loan portfolio under the new CECL (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 38,632
Loans placed on non-accrual	85,300
Commercial real estate: | Commercial investor real estate
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	8,437
Commercial real estate: | Commercial owner-occupied real estate
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	4,148
Commercial real estate: | Commercial AD&C
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	829
Commercial Business
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	8,450
Residential real estate: | Residential mortgage
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	12,661
Residential real estate: | Residential construction
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	0
Consumer
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	4,107
Non-accrual status
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	38,632
PCD loans designated as non-accrual	13,084
Loans placed on non-accrual	85,286
Non-accrual balances transferred to OREO	(70)
Non-accrual balances charged-off	(1,394)
Net payments or draws	(21,201)
Non-accrual loans brought current	(1,976)
Balance at end of period	112,361
Non-accrual status | Commercial real estate: | Commercial investor real estate
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	8,437
PCD loans designated as non-accrual	9,544
Loans placed on non-accrual	37,882
Non-accrual balances transferred to OREO	0
Non-accrual balances charged-off	(411)
Net payments or draws	(10,225)
Non-accrual loans brought current	0
Balance at end of period	45,227
Non-accrual status | Commercial real estate: | Commercial owner-occupied real estate
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	4,148
PCD loans designated as non-accrual	0
Loans placed on non-accrual	8,572
Non-accrual balances transferred to OREO	0
Non-accrual balances charged-off	0
Net payments or draws	(1,059)
Non-accrual loans brought current	(100)
Balance at end of period	11,561
Non-accrual status | Commercial real estate: | Commercial AD&C
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	829
PCD loans designated as non-accrual	0
Loans placed on non-accrual	15,844
Non-accrual balances transferred to OREO	0
Non-accrual balances charged-off	0
Net payments or draws	(1,629)
Non-accrual loans brought current	0
Balance at end of period	15,044
Non-accrual status | Commercial Business
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	8,450
PCD loans designated as non-accrual	2,539
Loans placed on non-accrual	17,442
Non-accrual balances transferred to OREO	0
Non-accrual balances charged-off	(446)
Net payments or draws	(4,169)
Non-accrual loans brought current	(883)
Balance at end of period	22,933
Non-accrual status | Residential real estate: | Residential mortgage
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	12,661
PCD loans designated as non-accrual	8
Loans placed on non-accrual	1,485
Non-accrual balances transferred to OREO	(70)
Non-accrual balances charged-off	(416)
Net payments or draws	(2,598)
Non-accrual loans brought current	(858)
Balance at end of period	10,212
Non-accrual status | Residential real estate: | Residential construction
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	0
PCD loans designated as non-accrual	0
Loans placed on non-accrual	0
Non-accrual balances transferred to OREO	0
Non-accrual balances charged-off	0
Net payments or draws	0
Non-accrual loans brought current	0
Balance at end of period	0
Non-accrual status | Consumer
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	4,107
PCD loans designated as non-accrual	993
Loans placed on non-accrual	4,061
Non-accrual balances transferred to OREO	0
Non-accrual balances charged-off	(121)
Net payments or draws	(1,521)
Non-accrual loans brought current	(135)
Balance at end of period	$ 7,384

CREDIT QUALITY ASSESSMENT - Cre

CREDIT QUALITY ASSESSMENT - Credit Quality of Loan Portfolio, New (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Past due		$ 27,748
Non-accrual loans		38,632
Loans greater than 90 days past due		0
Restructured loans		2,636
Total	$ 10,400,509	6,705,232
Performing loans:
Financing Receivable, Past Due [Line Items]
Current	10,226,191
Total performing loans	10,285,057
Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	112,361
Loans greater than 90 days past due	774
Restructured loans	2,317
Total non-performing loans	115,452
30-59 days
Financing Receivable, Past Due [Line Items]
Past due		19,986
30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Past due	46,812
60-89 days
Financing Receivable, Past Due [Line Items]
Past due		7,762
60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Past due	12,054
Commercial investor real estate
Financing Receivable, Past Due [Line Items]
Total	3,634,720
Commercial owner-occupied real estate
Financing Receivable, Past Due [Line Items]
Total	1,642,216
Commercial AD&C
Financing Receivable, Past Due [Line Items]
Total	1,050,973
Residential mortgage
Financing Receivable, Past Due [Line Items]
Total	1,105,179
Residential construction
Financing Receivable, Past Due [Line Items]
Total	182,619
Commercial real estate: | Commercial investor real estate
Financing Receivable, Past Due [Line Items]
Past due		932
Non-accrual loans		8,437
Loans greater than 90 days past due		0
Restructured loans		775
Total	3,634,720	2,169,156
Commercial real estate: | Commercial investor real estate | Performing loans:
Financing Receivable, Past Due [Line Items]
Current	3,571,184
Total performing loans	3,589,360
Commercial real estate: | Commercial investor real estate | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	45,227
Loans greater than 90 days past due	133
Restructured loans	0
Total non-performing loans	45,360
Commercial real estate: | Commercial investor real estate | 30-59 days
Financing Receivable, Past Due [Line Items]
Past due		932
Commercial real estate: | Commercial investor real estate | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Past due	14,046
Commercial real estate: | Commercial investor real estate | 60-89 days
Financing Receivable, Past Due [Line Items]
Past due		0
Commercial real estate: | Commercial investor real estate | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Past due	4,130
Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Past Due [Line Items]
Past due		316
Non-accrual loans		4,148
Loans greater than 90 days past due		0
Restructured loans		0
Total	1,642,216	1,288,677
Commercial real estate: | Commercial owner-occupied real estate | Performing loans:
Financing Receivable, Past Due [Line Items]
Current	1,624,265
Total performing loans	1,630,655
Commercial real estate: | Commercial owner-occupied real estate | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	11,561
Loans greater than 90 days past due	0
Restructured loans	0
Total non-performing loans	11,561
Commercial real estate: | Commercial owner-occupied real estate | 30-59 days
Financing Receivable, Past Due [Line Items]
Past due		316
Commercial real estate: | Commercial owner-occupied real estate | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Past due	6,390
Commercial real estate: | Commercial owner-occupied real estate | 60-89 days
Financing Receivable, Past Due [Line Items]
Past due		0
Commercial real estate: | Commercial owner-occupied real estate | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Past due	0
Commercial real estate: | Commercial AD&C
Financing Receivable, Past Due [Line Items]
Past due		0
Non-accrual loans		829
Loans greater than 90 days past due		0
Restructured loans		0
Total	1,050,973	684,010
Commercial real estate: | Commercial AD&C | Performing loans:
Financing Receivable, Past Due [Line Items]
Current	1,033,057
Total performing loans	1,035,929
Commercial real estate: | Commercial AD&C | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	15,044
Loans greater than 90 days past due	0
Restructured loans	0
Total non-performing loans	15,044
Commercial real estate: | Commercial AD&C | 30-59 days
Financing Receivable, Past Due [Line Items]
Past due		0
Commercial real estate: | Commercial AD&C | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Past due	29
Commercial real estate: | Commercial AD&C | 60-89 days
Financing Receivable, Past Due [Line Items]
Past due		0
Commercial real estate: | Commercial AD&C | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Past due	2,843
Commercial Business
Financing Receivable, Past Due [Line Items]
Non-accrual loans		8,450
Loans greater than 90 days past due		0
Restructured loans		417
Total	8,595,457	4,942,862
Commercial Business | Commercial business
Financing Receivable, Past Due [Line Items]
Past due		1,278
Non-accrual loans		8,450
Total	2,267,548	801,019
Commercial Business | Commercial business | Performing loans:
Financing Receivable, Past Due [Line Items]
Current	2,238,617
Total performing loans	2,243,739
Commercial Business | Commercial business | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	22,933
Loans greater than 90 days past due	161
Restructured loans	715
Total non-performing loans	23,809
Commercial Business | Commercial business | 30-59 days
Financing Receivable, Past Due [Line Items]
Past due		908
Commercial Business | Commercial business | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Past due	4,859
Commercial Business | Commercial business | 60-89 days
Financing Receivable, Past Due [Line Items]
Past due		370
Commercial Business | Commercial business | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Past due	263
Residential real estate: | Residential mortgage
Financing Receivable, Past Due [Line Items]
Past due		19,394
Non-accrual loans		12,661
Loans greater than 90 days past due		0
Restructured loans		1,080
Total	1,105,179	1,149,327
Residential real estate: | Residential mortgage | Performing loans:
Financing Receivable, Past Due [Line Items]
Current	1,073,963
Total performing loans	1,092,885
Residential real estate: | Residential mortgage | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	10,212
Loans greater than 90 days past due	480
Restructured loans	1,602
Total non-performing loans	12,294
Residential real estate: | Residential mortgage | 30-59 days
Financing Receivable, Past Due [Line Items]
Past due		14,853
Residential real estate: | Residential mortgage | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Past due	16,213
Residential real estate: | Residential mortgage | 60-89 days
Financing Receivable, Past Due [Line Items]
Past due		4,541
Residential real estate: | Residential mortgage | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Past due	2,709
Residential real estate: | Residential construction
Financing Receivable, Past Due [Line Items]
Past due		1,614
Non-accrual loans		0
Loans greater than 90 days past due		0
Restructured loans		0
Total	182,619	146,279
Residential real estate: | Residential construction | Performing loans:
Financing Receivable, Past Due [Line Items]
Current	182,557
Total performing loans	182,619
Residential real estate: | Residential construction | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	0
Loans greater than 90 days past due	0
Restructured loans	0
Total non-performing loans	0
Residential real estate: | Residential construction | 30-59 days
Financing Receivable, Past Due [Line Items]
Past due		280
Residential real estate: | Residential construction | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Past due	0
Residential real estate: | Residential construction | 60-89 days
Financing Receivable, Past Due [Line Items]
Past due		1,334
Residential real estate: | Residential construction | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Past due	62
Consumer
Financing Receivable, Past Due [Line Items]
Past due		4,214
Non-accrual loans		4,107
Loans greater than 90 days past due		0
Restructured loans		364
Total	517,254	466,764
Consumer | Performing loans:
Financing Receivable, Past Due [Line Items]
Current	502,548
Total performing loans	509,870
Consumer | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	7,384
Loans greater than 90 days past due	0
Restructured loans	0
Total non-performing loans	7,384
Consumer | 30-59 days
Financing Receivable, Past Due [Line Items]
Past due		2,697
Consumer | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Past due	5,275
Consumer | 60-89 days
Financing Receivable, Past Due [Line Items]
Past due		$ 1,517
Consumer | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Past due	$ 2,047

CREDIT QUALITY ASSESSMENT - I_2

CREDIT QUALITY ASSESSMENT - Information about credit quality indicator by year of origination (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 3,305,720
2019	1,774,275
2018	1,179,845
2017	1,016,641
2016	866,898
Prior	1,242,626
Revolving Loans	1,014,504
Total	10,400,509	$ 6,705,232
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total		4,892,398
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total		7,960
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total		42,504
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total		0
Commercial investor real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	922,059
2019	767,459
2018	466,934
2017	470,150
2016	470,019
Prior	504,568
Revolving Loans	33,531
Total	3,634,720
Commercial investor real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	910,426
2019	763,214
2018	448,406
2017	448,698
2016	469,077
Prior	498,384
Revolving Loans	33,531
Total	3,571,736
Commercial investor real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2020	11,044
2019	0
2018	4,879
2017	833
2016	269
Prior	27
Revolving Loans	0
Total	17,052
Commercial investor real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2020	589
2019	4,245
2018	13,649
2017	20,619
2016	673
Prior	6,157
Revolving Loans	0
Total	45,932
Commercial investor real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans	0
Total	0
Commercial owner-occupied real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	289,210
2019	389,393
2018	239,670
2017	197,841
2016	205,278
Prior	319,160
Revolving Loans	1,664
Total	1,642,216
Commercial owner-occupied real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	285,310
2019	385,058
2018	234,578
2017	192,634
2016	204,925
Prior	306,840
Revolving Loans	1,664
Total	1,611,009
Commercial owner-occupied real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,290
2019	0
2018	3,027
2017	4,742
2016	134
Prior	4,079
Revolving Loans	0
Total	14,272
Commercial owner-occupied real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,610
2019	4,335
2018	2,065
2017	465
2016	219
Prior	8,009
Revolving Loans	0
Total	16,703
Commercial owner-occupied real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	232
Revolving Loans	0
Total	232
Commercial AD&C
Financing Receivable, Credit Quality Indicator [Line Items]
2020	488,781
2019	262,428
2018	149,703
2017	64,008
2016	2,932
Prior	2,357
Revolving Loans	80,764
Total	1,050,973
Commercial AD&C | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	485,631
2019	261,537
2018	149,703
2017	50,192
2016	89
Prior	2,357
Revolving Loans	80,764
Total	1,030,273
Commercial AD&C | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,711
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans	0
Total	1,711
Commercial AD&C | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,439
2019	891
2018	0
2017	13,816
2016	2,843
Prior	0
Revolving Loans	0
Total	18,989
Commercial AD&C | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans	0
Total	0
Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
2020	236,909
2019	85,106
2018	158,382
2017	188,970
2016	143,557
Prior	292,255
Revolving Loans	0
Total	1,105,179
Residential mortgage | 660-850
Financing Receivable, Credit Quality Indicator [Line Items]
2020	229,033
2019	74,054
2018	138,824
2017	172,493
2016	129,701
Prior	251,065
Revolving Loans	0
Total	995,170
Residential mortgage | 600-659
Financing Receivable, Credit Quality Indicator [Line Items]
2020	4,824
2019	7,706
2018	10,763
2017	11,719
2016	8,173
Prior	21,424
Revolving Loans	0
Total	64,609
Residential mortgage | 540-599
Financing Receivable, Credit Quality Indicator [Line Items]
2020	350
2019	1,238
2018	5,219
2017	2,608
2016	4,791
Prior	10,167
Revolving Loans	0
Total	24,373
Residential mortgage | less than 540
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,702
2019	2,108
2018	3,576
2017	2,150
2016	892
Prior	9,599
Revolving Loans	0
Total	21,027
Residential construction
Financing Receivable, Credit Quality Indicator [Line Items]
2020	115,201
2019	47,836
2018	14,543
2017	2,805
2016	2,062
Prior	0
Revolving Loans	172
Total	182,619
Residential construction | 660-850
Financing Receivable, Credit Quality Indicator [Line Items]
2020	112,604
2019	44,647
2018	14,543
2017	2,805
2016	1,693
Prior	0
Revolving Loans	172
Total	176,464
Residential construction | 600-659
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,743
2019	3,189
2018	0
2017	0
2016	0
Prior	0
Revolving Loans	0
Total	4,932
Residential construction | 540-599
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	369
Prior	0
Revolving Loans	0
Total	369
Residential construction | less than 540
Financing Receivable, Credit Quality Indicator [Line Items]
2020	854
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans	0
Total	854
Commercial Business
Financing Receivable, Credit Quality Indicator [Line Items]
Total	8,595,457	4,942,862
Commercial Business | Commercial business
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,249,771
2019	215,623
2018	144,348
2017	89,205
2016	38,836
Prior	87,689
Revolving Loans	442,076
Total	2,267,548	801,019
Commercial Business | Commercial business | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,244,822
2019	208,682
2018	138,861
2017	86,830
2016	34,498
Prior	81,760
Revolving Loans	433,016
Total	2,228,469	783,909
Commercial Business | Commercial business | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,929
2019	1,382
2018	1,119
2017	708
2016	309
Prior	621
Revolving Loans	4,319
Total	10,387	2,487
Commercial Business | Commercial business | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,914
2019	4,564
2018	3,519
2017	1,631
2016	2,745
Prior	3,456
Revolving Loans	1,829
Total	20,658	14,623
Commercial Business | Commercial business | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2020	106
2019	995
2018	849
2017	36
2016	1,284
Prior	1,852
Revolving Loans	2,912
Total	8,034	0
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	3,789
2019	6,430
2018	6,265
2017	3,662
2016	4,214
Prior	36,597
Revolving Loans	456,297
Total	517,254	$ 466,764
Consumer | 660-850
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,575
2019	4,609
2018	5,112
2017	2,110
2016	2,614
Prior	24,444
Revolving Loans	417,737
Total	459,201
Consumer | 600-659
Financing Receivable, Credit Quality Indicator [Line Items]
2020	374
2019	445
2018	334
2017	428
2016	467
Prior	5,401
Revolving Loans	21,052
Total	28,501
Consumer | 540-599
Financing Receivable, Credit Quality Indicator [Line Items]
2020	89
2019	1,216
2018	294
2017	339
2016	601
Prior	3,926
Revolving Loans	6,153
Total	12,618
Consumer | less than 540
Financing Receivable, Credit Quality Indicator [Line Items]
2020	751
2019	160
2018	525
2017	785
2016	532
Prior	2,826
Revolving Loans	11,355
Total	$ 16,934

CREDIT QUALITY ASSESSMENT - His

CREDIT QUALITY ASSESSMENT - Historical information on the credit quality of the loan portfolio under the legacy disclosure (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Non-accrual loans		$ 38,632
Loans 90 days past due		0
Restructured loans		2,636
Total non-performing loans		41,268
Other real estate owned	$ 1,455	1,482
Total non-performing assets		42,750
Commercial real estate: | Commercial investor real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Non-accrual loans		8,437
Loans 90 days past due		0
Restructured loans		775
Total non-performing loans		9,212
Other real estate owned		409
Total non-performing assets		9,621
Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Non-accrual loans		4,148
Loans 90 days past due		0
Restructured loans		0
Total non-performing loans		4,148
Other real estate owned		0
Total non-performing assets		4,148
Commercial real estate: | Commercial AD&C
Financing Receivable, Credit Quality Indicator [Line Items]
Non-accrual loans		829
Loans 90 days past due		0
Restructured loans		0
Total non-performing loans		829
Other real estate owned		665
Total non-performing assets		1,494
Commercial Business
Financing Receivable, Credit Quality Indicator [Line Items]
Non-accrual loans		8,450
Loans 90 days past due		0
Restructured loans		417
Total non-performing loans		8,867
Other real estate owned		39
Total non-performing assets		8,906
Residential real estate: | Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Non-accrual loans		12,661
Loans 90 days past due		0
Restructured loans		1,080
Total non-performing loans		13,741
Other real estate owned		305
Total non-performing assets		14,046
Residential real estate: | Residential construction
Financing Receivable, Credit Quality Indicator [Line Items]
Non-accrual loans		0
Loans 90 days past due		0
Restructured loans		0
Total non-performing loans		0
Other real estate owned		0
Total non-performing assets		0
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Non-accrual loans		4,107
Loans 90 days past due		0
Restructured loans		364
Total non-performing loans		4,471
Other real estate owned	$ 300	64
Total non-performing assets		$ 4,535

CREDIT QUALITY ASSESSMENT - C_3

CREDIT QUALITY ASSESSMENT - Credit Quality of Loan Portfolio (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Total past due		$ 27,748
Non-accrual loans		38,632
Loans acquired with deteriorated credit quality		13,084
Current loans		6,625,768
Total	$ 10,400,509	6,705,232
Commercial investor real estate
Financing Receivable, Past Due [Line Items]
Total	3,634,720
Commercial owner-occupied real estate
Financing Receivable, Past Due [Line Items]
Total	1,642,216
Commercial AD&C
Financing Receivable, Past Due [Line Items]
Total	1,050,973
Residential mortgage
Financing Receivable, Past Due [Line Items]
Total	1,105,179
Residential construction
Financing Receivable, Past Due [Line Items]
Total	182,619
Commercial real estate: | Commercial investor real estate
Financing Receivable, Past Due [Line Items]
Total past due		932
Non-accrual loans		8,437
Loans acquired with deteriorated credit quality		9,544
Current loans		2,150,243
Total	3,634,720	2,169,156
Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Past Due [Line Items]
Total past due		316
Non-accrual loans		4,148
Loans acquired with deteriorated credit quality		0
Current loans		1,284,213
Total	1,642,216	1,288,677
Commercial real estate: | Commercial AD&C
Financing Receivable, Past Due [Line Items]
Total past due		0
Non-accrual loans		829
Loans acquired with deteriorated credit quality		0
Current loans		683,181
Total	1,050,973	684,010
Commercial Business
Financing Receivable, Past Due [Line Items]
Non-accrual loans		8,450
Total	8,595,457	4,942,862
Commercial Business | Commercial business
Financing Receivable, Past Due [Line Items]
Total past due		1,278
Non-accrual loans		8,450
Loans acquired with deteriorated credit quality		2,539
Current loans		788,752
Total	2,267,548	801,019
Residential real estate: | Residential mortgage
Financing Receivable, Past Due [Line Items]
Total past due		19,394
Non-accrual loans		12,661
Loans acquired with deteriorated credit quality		8
Current loans		1,117,264
Total	1,105,179	1,149,327
Residential real estate: | Residential construction
Financing Receivable, Past Due [Line Items]
Total past due		1,614
Non-accrual loans		0
Loans acquired with deteriorated credit quality		0
Current loans		144,665
Total	182,619	146,279
Consumer
Financing Receivable, Past Due [Line Items]
Total past due		4,214
Non-accrual loans		4,107
Loans acquired with deteriorated credit quality		993
Current loans		457,450
Total	$ 517,254	466,764
30-59 days
Financing Receivable, Past Due [Line Items]
Total past due		19,986
30-59 days | Commercial real estate: | Commercial investor real estate
Financing Receivable, Past Due [Line Items]
Total past due		932
30-59 days | Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Past Due [Line Items]
Total past due		316
30-59 days | Commercial real estate: | Commercial AD&C
Financing Receivable, Past Due [Line Items]
Total past due		0
30-59 days | Commercial Business | Commercial business
Financing Receivable, Past Due [Line Items]
Total past due		908
30-59 days | Residential real estate: | Residential mortgage
Financing Receivable, Past Due [Line Items]
Total past due		14,853
30-59 days | Residential real estate: | Residential construction
Financing Receivable, Past Due [Line Items]
Total past due		280
30-59 days | Consumer
Financing Receivable, Past Due [Line Items]
Total past due		2,697
60-89 days
Financing Receivable, Past Due [Line Items]
Total past due		7,762
60-89 days | Commercial real estate: | Commercial investor real estate
Financing Receivable, Past Due [Line Items]
Total past due		0
60-89 days | Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Past Due [Line Items]
Total past due		0
60-89 days | Commercial real estate: | Commercial AD&C
Financing Receivable, Past Due [Line Items]
Total past due		0
60-89 days | Commercial Business | Commercial business
Financing Receivable, Past Due [Line Items]
Total past due		370
60-89 days | Residential real estate: | Residential mortgage
Financing Receivable, Past Due [Line Items]
Total past due		4,541
60-89 days | Residential real estate: | Residential construction
Financing Receivable, Past Due [Line Items]
Total past due		1,334
60-89 days | Consumer
Financing Receivable, Past Due [Line Items]
Total past due		1,517
> 90 days
Financing Receivable, Past Due [Line Items]
Total past due		0
> 90 days | Commercial real estate: | Commercial investor real estate
Financing Receivable, Past Due [Line Items]
Total past due		0
> 90 days | Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Past Due [Line Items]
Total past due		0
> 90 days | Commercial real estate: | Commercial AD&C
Financing Receivable, Past Due [Line Items]
Total past due		0
> 90 days | Commercial Business | Commercial business
Financing Receivable, Past Due [Line Items]
Total past due		0
> 90 days | Residential real estate: | Residential mortgage
Financing Receivable, Past Due [Line Items]
Total past due		0
> 90 days | Residential real estate: | Residential construction
Financing Receivable, Past Due [Line Items]
Total past due		0
> 90 days | Consumer
Financing Receivable, Past Due [Line Items]
Total past due		$ 0

CREDIT QUALITY ASSESSMENT - C_4

CREDIT QUALITY ASSESSMENT - Credit Risk Rating Indicators for Each Segment of Commercial Loan Portfolio (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	$ 10,400,509	$ 6,705,232
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		4,942,862
Commercial investor real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	3,634,720
Commercial owner-occupied real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	1,642,216
Commercial AD&C
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	1,050,973
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		4,892,398
Pass | Commercial investor real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	3,571,736
Pass | Commercial owner-occupied real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	1,611,009
Pass | Commercial AD&C
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	1,030,273
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		7,960
Special Mention | Commercial investor real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	17,052
Special Mention | Commercial owner-occupied real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	14,272
Special Mention | Commercial AD&C
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	1,711
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		42,504
Substandard | Commercial investor real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	45,932
Substandard | Commercial owner-occupied real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	16,703
Substandard | Commercial AD&C
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	18,989
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		0
Doubtful | Commercial investor real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	0
Doubtful | Commercial owner-occupied real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	232
Doubtful | Commercial AD&C
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	0
Commercial real estate: | Commercial investor real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	3,634,720	2,169,156
Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	1,642,216	1,288,677
Commercial real estate: | Commercial AD&C
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	1,050,973	684,010
Commercial real estate: | Pass | Commercial investor real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		2,146,971
Commercial real estate: | Pass | Commercial owner-occupied real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		1,278,337
Commercial real estate: | Pass | Commercial AD&C
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		683,181
Commercial real estate: | Special Mention | Commercial investor real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		3,189
Commercial real estate: | Special Mention | Commercial owner-occupied real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		2,284
Commercial real estate: | Special Mention | Commercial AD&C
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		0
Commercial real estate: | Substandard | Commercial investor real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		18,996
Commercial real estate: | Substandard | Commercial owner-occupied real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		8,056
Commercial real estate: | Substandard | Commercial AD&C
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		829
Commercial real estate: | Doubtful | Commercial investor real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		0
Commercial real estate: | Doubtful | Commercial owner-occupied real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		0
Commercial real estate: | Doubtful | Commercial AD&C
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		0
Commercial Business
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	8,595,457	4,942,862
Commercial Business | Commercial business
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	2,267,548	801,019
Commercial Business | Pass | Commercial business
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	2,228,469	783,909
Commercial Business | Special Mention | Commercial business
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	10,387	2,487
Commercial Business | Substandard | Commercial business
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	20,658	14,623
Commercial Business | Doubtful | Commercial business
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	$ 8,034	$ 0

CREDIT QUALITY ASSESSMENT - I_3

CREDIT QUALITY ASSESSMENT - Information by Credit Risk Rating Indicators for Those Remaining Segments of Loan Portfolio (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 10,400,509	$ 6,705,232
Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,105,179
Residential construction
Financing Receivable, Credit Quality Indicator [Line Items]
Total	182,619
Residential real estate: | Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,105,179	1,149,327
Residential real estate: | Residential construction
Financing Receivable, Credit Quality Indicator [Line Items]
Total	182,619	146,279
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 517,254	466,764
Homogeneous Loan Pools
Financing Receivable, Credit Quality Indicator [Line Items]
Total		1,762,370
Homogeneous Loan Pools | Residential real estate: | Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total		1,149,327
Homogeneous Loan Pools | Residential real estate: | Residential construction
Financing Receivable, Credit Quality Indicator [Line Items]
Total		146,279
Homogeneous Loan Pools | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total		466,764
Homogeneous Loan Pools | Performing loans:
Financing Receivable, Credit Quality Indicator [Line Items]
Total		1,744,158
Homogeneous Loan Pools | Performing loans: | Residential real estate: | Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total		1,135,586
Homogeneous Loan Pools | Performing loans: | Residential real estate: | Residential construction
Financing Receivable, Credit Quality Indicator [Line Items]
Total		146,279
Homogeneous Loan Pools | Performing loans: | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total		462,293
Homogeneous Loan Pools | Non-performing loans: | 90 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total		0
Homogeneous Loan Pools | Non-performing loans: | Non-accruing
Financing Receivable, Credit Quality Indicator [Line Items]
Total		16,768
Homogeneous Loan Pools | Non-performing loans: | Restructured loans | Restructured loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total		1,444
Homogeneous Loan Pools | Non-performing loans: | Residential real estate: | Residential mortgage | 90 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total		0
Homogeneous Loan Pools | Non-performing loans: | Residential real estate: | Residential mortgage | Non-accruing
Financing Receivable, Credit Quality Indicator [Line Items]
Total		12,661
Homogeneous Loan Pools | Non-performing loans: | Residential real estate: | Residential mortgage | Restructured loans | Restructured loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total		1,080
Homogeneous Loan Pools | Non-performing loans: | Residential real estate: | Residential construction | 90 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total		0
Homogeneous Loan Pools | Non-performing loans: | Residential real estate: | Residential construction | Non-accruing
Financing Receivable, Credit Quality Indicator [Line Items]
Total		0
Homogeneous Loan Pools | Non-performing loans: | Residential real estate: | Residential construction | Restructured loans | Restructured loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total		0
Homogeneous Loan Pools | Non-performing loans: | Consumer | 90 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total		0
Homogeneous Loan Pools | Non-performing loans: | Consumer | Non-accruing
Financing Receivable, Credit Quality Indicator [Line Items]
Total		4,107
Homogeneous Loan Pools | Non-performing loans: | Consumer | Restructured loans | Restructured loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total		$ 364

CREDIT QUALITY ASSESSMENT - Res

CREDIT QUALITY ASSESSMENT - Restructured Loans at the date of Restructuring For Specific Segments of the Loan Portfolio (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Troubled Debt Restructuring [Line Items]
Balance	$ 4,533	$ 2,359
Specific allowance	1,020	401
Restructured and subsequently defaulted	0	0
All Other Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Balance	549	364
Specific allowance	0	0
Restructured and subsequently defaulted	0	0
Troubled debt restructurings:
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured accruing	929	1,309
Restructured non-accruing	3,604	1,050
Troubled debt restructurings: | All Other Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured accruing	549	364
Restructured non-accruing	0	0
Commercial real estate: | Commercial investor real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Balance	723	1,564
Specific allowance	65	205
Restructured and subsequently defaulted	0	0
Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Balance	930	0
Specific allowance	0	0
Restructured and subsequently defaulted	0	0
Commercial real estate: | Commercial AD&C
Financing Receivable, Troubled Debt Restructuring [Line Items]
Balance	0	0
Specific allowance	0	0
Restructured and subsequently defaulted	0	0
Commercial real estate: | Troubled debt restructurings: | Commercial investor real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured accruing	0	775
Restructured non-accruing	723	789
Commercial real estate: | Troubled debt restructurings: | Commercial owner-occupied real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured accruing	0	0
Restructured non-accruing	930	0
Commercial real estate: | Troubled debt restructurings: | Commercial AD&C
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured accruing	0	0
Restructured non-accruing	0	0
Commercial Business
Financing Receivable, Troubled Debt Restructuring [Line Items]
Balance	2,331	431
Specific allowance	955	196
Restructured and subsequently defaulted	0	0
Commercial Business | Troubled debt restructurings:
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured accruing	380	170
Restructured non-accruing	$ 1,951	$ 261

PREMISES AND EQUIPMENT - Narrat

PREMISES AND EQUIPMENT - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Depreciation and amortization	$ 8.5	$ 7.2	$ 7.2

PREMISES AND EQUIPMENT (Compone

PREMISES AND EQUIPMENT (Components of Premises and Equipment) (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Land	$ 13,262	$ 10,160
Buildings and leasehold improvements	70,776	70,812
Equipment	49,614	46,471
Total premises and equipment	133,652	127,443
Less: accumulated depreciation and amortization	(75,932)	(68,828)
Net premises and equipment	$ 57,720	$ 58,615

LEASES - Narrative (Details)

LEASES - Narrative (Details) $ in Thousands	Apr. 01, 2020USD ($)operating_leaselocation	Mar. 31, 2020USD ($)location	Dec. 31, 2020USD ($)operating_lease	Dec. 31, 2019USD ($)
Lessee, Lease, Description [Line Items]
Right-of-use asset obtained in exchange for operating lease liability			$ 871	$ 399
Operating lease liabilities			$ 74,982	76,871
Number of operating leases acquired likely to be terminated | operating_lease			7
Operating lease ROU assets			$ 65,215	$ 69,320
Branch Location
Lessee, Lease, Description [Line Items]
Number of operating leases acquired likely to be terminated | operating_lease			6
Office Space
Lessee, Lease, Description [Line Items]
Number of operating leases acquired likely to be terminated | operating_lease			1
Minimum
Lessee, Lease, Description [Line Items]
Renewal term			1 year
Maximum
Lessee, Lease, Description [Line Items]
Renewal term			20 years
Revere acquisition
Lessee, Lease, Description [Line Items]
Right-of-use asset obtained in exchange for operating lease liability	$ 7,400
Number of operating leases | operating_lease	15
Number of locations operating leases | location	12
Operating lease liabilities	$ 8,700
Liabilities arising from contingencies	1,100
Tenant improvements	200
Asset impairment charges	$ 2,300
Acquisition of Rembert Pendleton Jackson
Lessee, Lease, Description [Line Items]
Number of locations acquired | location		2
Right-of-use asset obtained in exchange for operating lease liability		$ 300
Lease operation commence in 2021
Lessee, Lease, Description [Line Items]
Operating lease liabilities			$ 2,100
Liabilities arising from contingencies			500
Tenant improvements			200
Operating lease ROU assets			$ 1,400

LEASES - Lease Cost (Details)

LEASES - Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Components of lease expense:
Operating lease cost (resulting from lease payments)	$ 12,453	$ 11,334
Acquisitions	$ 871	$ 399
Weighted average remaining lease term of operating leases	9 years 6 months	10 years 4 months 24 days
Weighted average discount rate of operating leases	3.04%	3.28%
Supplemental cash flow information related to leases:
Operating cash flows from operating leases	$ 13,571	$ 8,704
Operating lease ROU assets	65,215	69,320
Operating lease liabilities	$ 74,982	$ 76,871
Operating Lease, Liability, Statement of Financial Position [Extensible List]	sasr:AccruedInterestPayableAndOtherLiabilities	sasr:AccruedInterestPayableAndOtherLiabilities
Revere Bank And RPJ
Components of lease expense:
Acquisitions	$ 7,720	$ 0

LEASES - Maturities of operatin

LEASES - Maturities of operating lease liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
One year	$ 12,490
Two years	10,946
Three years	10,851
Four years	9,063
Five years	7,347
Thereafter	37,382
Total undiscounted lease payments	88,079
Less: Present value discount	(13,097)
Lease Liability	$ 74,982	$ 76,871
Operating Lease, Liability, Statement of Financial Position [Extensible List]	sasr:AccruedInterestPayableAndOtherLiabilities	sasr:AccruedInterestPayableAndOtherLiabilities

GOODWILL AND OTHER INTANGIBLE_3

GOODWILL AND OTHER INTANGIBLE ASSETS - Gross Carrying Amounts and Accumulated Amortization of Intangible Assets and Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 42,944	$ 12,156
Accumulated Amortization	(10,423)	(4,315)
Net Carrying Amount	32,521	7,841
Goodwill	370,223	347,149
Goodwill	370,223	347,149	$ 347,149
Core deposit intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	29,038	10,678
Accumulated Amortization	(7,969)	(3,689)
Net Carrying Amount	$ 21,069	$ 6,989
Core deposit intangibles | Weighted Average
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	8 years 4 months 24 days	8 years
Other identifiable intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 13,906	$ 1,478
Accumulated Amortization	(2,454)	(626)
Net Carrying Amount	$ 11,452	$ 852
Other identifiable intangibles | Weighted Average
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	10 years 8 months 12 days	9 years 8 months 12 days

GOODWILL AND OTHER INTANGIBLE_4

GOODWILL AND OTHER INTANGIBLE ASSETS - Net Carrying Amount of Goodwill By Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Beginning balance	$ 347,149	$ 347,149
Acquisitions		0
Ending balance	370,223	347,149
Acquisition of Rembert Pendleton Jackson
Goodwill [Roll Forward]
Acquisitions	22,559
Acquisition of Revere Bank
Goodwill [Roll Forward]
Acquisitions	515
Community Banking
Goodwill [Roll Forward]
Beginning balance	331,173	331,173
Acquisitions		0
Ending balance	331,688	331,173
Community Banking | Acquisition of Rembert Pendleton Jackson
Goodwill [Roll Forward]
Acquisitions	0
Community Banking | Acquisition of Revere Bank
Goodwill [Roll Forward]
Acquisitions	515
Insurance
Goodwill [Roll Forward]
Beginning balance	6,788	6,788
Acquisitions		0
Ending balance	6,788	6,788
Insurance | Acquisition of Rembert Pendleton Jackson
Goodwill [Roll Forward]
Acquisitions	0
Insurance | Acquisition of Revere Bank
Goodwill [Roll Forward]
Acquisitions	0
Investment Management
Goodwill [Roll Forward]
Beginning balance	9,188	9,188
Acquisitions		0
Ending balance	31,747	$ 9,188
Investment Management | Acquisition of Rembert Pendleton Jackson
Goodwill [Roll Forward]
Acquisitions	22,559
Investment Management | Acquisition of Revere Bank
Goodwill [Roll Forward]
Acquisitions	$ 0

GOODWILL AND OTHER INTANGIBLE_5

GOODWILL AND OTHER INTANGIBLE ASSETS - Estimated Future Amortization Expense for Amortizing Intangibles (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2021	$ 6,600
2022	5,844
2023	5,089
2024	4,333
2025	3,567
Thereafter	7,088
Total amortizing intangible assets	$ 32,521

DEPOSITS (Composition of Deposi

DEPOSITS (Composition of Deposits) (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deposits [Abstract]
Noninterest-bearing deposits	$ 3,325,547	$ 1,892,052
Interest-bearing deposits:
Demand	1,292,164	836,433
Money market savings	3,339,645	1,839,593
Regular savings	418,051	329,919
Time deposits of less than $100,000	509,919	463,431
Time deposits greater than $100,000 and less than $250,000	670,717	682,936
Time deposits of $250,000 or more	477,026	395,955
Total interest-bearing deposits	6,707,522	4,548,267
Total deposits	$ 10,033,069	$ 6,440,319

DEPOSITS - Narrative (Detail)

DEPOSITS - Narrative (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Time Deposits [Line Items]
Deposit liabilities reclassified as loans receivable	$ 13,100	$ 1,400
Percentage of time deposits, greater than $100,000 and less than $250,000 of total deposits	6.70%
Percentage of time deposits of $250,000 or more of total deposits	4.80%
Interest Expense, Time Deposits, Greater Than $100,000 And Less Than $250,000	$ 8,100	10,800	$ 9,500
Time deposits, $250,000 or more	10,700	13,000	$ 3,000
Total deposits	10,033,069	6,440,319
Director and Executive Officer
Time Deposits [Line Items]
Total deposits	$ 73,400	$ 29,900

DEPOSITS - Maturity Schedule fo

DEPOSITS - Maturity Schedule for Time Deposits (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Deposits [Abstract]
2021	$ 1,208,915
2022	275,872
2023	84,093
2024	73,859
2025	14,745
Thereafter	178
Total time deposits	$ 1,657,662

DEPOSITS - Months to Maturities

DEPOSITS - Months to Maturities Of Time Deposits (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Time deposits - $100,000 to $250,000
3 or Less	$ 211,006
Over 3 to 6	127,934
Over 6 to 12	139,133
Over 12	192,644
Total	670,717	$ 682,936
Time deposits - $250,000 or more
3 or Less	111,332
Over 3 to 6	115,678
Over 6 to 12	140,231
Over 12	109,785
Time deposits of $250,000 or more	$ 477,026	$ 395,955

BORROWINGS - Narrative (Detail)

BORROWINGS - Narrative (Detail) - USD ($)	Nov. 05, 2019	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Oct. 05, 2020
Subordinated debentures [Line Items]:
Subordinated debt		$ 227,088,000		$ 227,088,000	$ 209,406,000
Repayments of subordinated debt				$ 10,310,000	0	$ 0
Percentage of principal and accrued interest of retail repurchase agreements collateralized		102.50%		102.50%
Long-term debt		$ 1,149,320,000		$ 1,149,320,000	936,788,000
Federal Home Loan Bank Advances
Subordinated debentures [Line Items]:
Line of credit amount available for borrowing		3,000,000,000		3,000,000,000	2,400,000,000
Long-term line of credit		379,100,000		379,100,000	513,800,000
Federal Home Loan Bank Advances | Residential mortgage
Subordinated debentures [Line Items]:
Loans Pledged as Collateral		1,000,000,000		1,000,000,000
Federal Home Loan Bank Advances | Commercial real estate loans
Subordinated debentures [Line Items]:
Loans Pledged as Collateral		2,800,000,000		2,800,000,000	1,900,000,000
Federal Home Loan Bank Advances | HELOC
Subordinated debentures [Line Items]:
Loans Pledged as Collateral		226,200,000		226,200,000	266,800,000
Federal Home Loan Bank Advances | Multifamily Loans
Subordinated debentures [Line Items]:
Loans Pledged as Collateral		237,600,000		237,600,000	109,700,000
Federal Reserve and Correspondent Banks
Subordinated debentures [Line Items]:
Line of credit amount available for borrowing		276,200,000		276,200,000	463,300,000
Unsecured lines of credit, correspondent banks
Subordinated debentures [Line Items]:
Line of credit amount available for borrowing		1,100,000,000		1,100,000,000	730,000,000
Residential Portfolio Segment
Subordinated debentures [Line Items]:
Pledged under blanket lien					1,000,000,000
Subordinated Debt
Subordinated debentures [Line Items]:
Subordinated debt		227,088,000		227,088,000	199,009,000
Add: Purchase accounting premium		1,669,000		1,669,000	1,894,000
Subordinated Debt | WashingtonFirst Bankshares Inc
Subordinated debentures [Line Items]:
Subordinated debt		$ 25,000,000		$ 25,000,000
Interest rate		4.81%		4.81%			6.00%
Add: Purchase accounting premium		$ 2,200,000		$ 2,200,000
Debt instrument, term				10 years
Basis spread on variable rate		4.57%
Subordinated Debt | Revere acquisition
Subordinated debentures [Line Items]:
Subordinated debt		$ 31,000,000		$ 31,000,000
Interest rate		5.625%		5.625%
Add: Purchase accounting premium		$ 200,000		$ 200,000
Basis spread on variable rate				4.41%
Subordinated Debt | Fixed Floating Rate Subordinated Notes
Subordinated debentures [Line Items]:
Subordinated debt	$ 175,000,000
Interest rate	4.25%
Unamortized discount (premium) and debt issuance costs, net		2,900,000		$ 2,900,000
Basis spread on variable rate	2.62%
Subordinated Debt | Tier 2 Capital | WashingtonFirst Bankshares Inc
Subordinated debentures [Line Items]:
Subordinated debt		20,000,000		20,000,000
Junior Subordinated Debt
Subordinated debentures [Line Items]:
Subordinated debt		0		0	10,397,000
Add: Purchase accounting premium		0		0	$ 87,000
Junior Subordinated Debt | WashingtonFirst Bankshares Inc
Subordinated debentures [Line Items]:
Subordinated debt		10,300,000		10,300,000
Add: Purchase accounting premium		100,000		100,000
Repayments of subordinated debt			$ 10,300,000
Federal funds under the PPPLF program
Subordinated debentures [Line Items]:
Remaining borrowing capacity		1,100,000,000		1,100,000,000
Long-term debt		0		0
Federal funds purchased
Subordinated debentures [Line Items]:
Long-term debt		$ 390,000,000		$ 390,000,000

BORROWINGS - Schedule of Subord

BORROWINGS - Schedule of Subordinated Borrowing (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Oct. 05, 2020	Dec. 31, 2019
Subordinated Borrowing [Line Items]
Subordinated debt	$ 227,088		$ 209,406
Subordinated Debt
Subordinated Borrowing [Line Items]
Subordinated debt, gross	231,000		200,000
Less: Debt issuance costs	2,581		2,885
Subordinated debt	227,088		199,009
Add: Purchase accounting premium	1,669		1,894
Subordinated Debt | Fixed Floating
Subordinated Borrowing [Line Items]
Subordinated debt, gross	$ 175,000		175,000
Interest rate	4.25%
Subordinated Debt | WashingtonFirst Bankshares Inc
Subordinated Borrowing [Line Items]
Subordinated debt, gross	$ 25,000		25,000
Subordinated debt	25,000
Add: Purchase accounting premium	$ 2,200
Interest rate	4.81%	6.00%
Subordinated Debt | Revere acquisition
Subordinated Borrowing [Line Items]
Subordinated debt, gross	$ 31,000		0
Subordinated debt	31,000
Add: Purchase accounting premium	$ 200
Interest rate	5.625%
Subordinated Debt | WashingtonFirst Bankshares Inc And Revere
Subordinated Borrowing [Line Items]
Less: WashingtonFirst and Revere sub debt held as investments by Sandy Spring	$ (3,000)		0
Junior Subordinated Debt
Subordinated Borrowing [Line Items]
Subordinated debt, gross	0		10,310
Subordinated debt	0		10,397
Add: Purchase accounting premium	0		$ 87
Junior Subordinated Debt | WashingtonFirst Bankshares Inc
Subordinated Borrowing [Line Items]
Subordinated debt	10,300
Add: Purchase accounting premium	$ 100

BORROWINGS - Retail Repurchase

BORROWINGS - Retail Repurchase Agreements And Other Short Term Borrowings (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retail repurchase agreements
Short-term Debt [Line Items]
Other short-term borrowings	$ 153,157	$ 138,605	$ 137,429
Short-term debt, average outstanding amount	142,283	134,070	142,938
Other short term borrowings, maximum month end balance	$ 153,157	$ 152,685	$ 154,435
Interest rate	0.11%	0.58%	0.51%
Weighted average interest rate, over time	0.32%	0.54%	0.34%
Federal funds purchased
Short-term Debt [Line Items]
Other short-term borrowings	$ 390,000	$ 75,000	$ 0
Short-term debt, average outstanding amount	367,240	17,373	0
Other short term borrowings, maximum month end balance	$ 921,289	$ 75,000	$ 0
Interest rate	0.10%	1.62%	0.00%
Weighted average interest rate, over time	0.41%	2.43%	0.00%

BORROWINGS - Advances from FHLB

BORROWINGS - Advances from FHLB and Respective Maturity Schedule (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Maturity:
One year	$ 230,243	$ 134,167
Two years	76,332	230,445
Three years	72,500	76,665
Four years	0	72,500
Five years	0	0
After five years	0	0
Total advances from FHLB	$ 379,075	$ 513,777
Maturity:
One year	2.39%	2.13%
Two years	2.37%	2.39%
Three years	3.12%	2.37%
Four years	0.00%	3.12%
Five years	0.00%	0.00%
After five years	0.00%	0.00%
Total advances from FHLB	2.52%	2.42%

STOCKHOLDERS EQUITY - Narrative

STOCKHOLDERS EQUITY - Narrative (Detail) - USD ($)	Jul. 01, 2011	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Nov. 18, 2020
Equity, Class of Treasury Stock [Line Items]
Common stock, shares authorized (in shares)		100,000,000	100,000,000	100,000,000
Common stock, par value (in dollars per share)		$ 1	$ 1	$ 1
Stock repurchased and retired (in shares)		820,328	668,191
Dividend Reinvestment Plan
Equity, Class of Treasury Stock [Line Items]
Additional dividends potential payment		$ 144,900,000
Due to related parties		$ 0	$ 0	$ 0
2020 Stock Repurchase Plan
Equity, Class of Treasury Stock [Line Items]
Repurchase of outstanding shares of common stock under Stock Repurchase Program		2,350,000		2,350,000
Common Stock | Director Plan
Equity, Class of Treasury Stock [Line Items]
Common stock, shares authorized (in shares)		45,000		45,000
Shares available for issuance (in shares)		24,424		24,424
Common Stock | Director Plan | Minimum
Equity, Class of Treasury Stock [Line Items]
Percentage of fee of annual retainer fee to purchase shares		50.00%		50.00%
Common Stock | Employee Stock Purchase Plan
Equity, Class of Treasury Stock [Line Items]
Common stock, shares authorized (in shares)	300,000
Maximum contribution amount	$ 25,000
Common Stock | Restated Employee Stock Purchase Plan
Equity, Class of Treasury Stock [Line Items]
Common stock, shares authorized (in shares)					700,000
Shares available for issuance (in shares)		707,153		707,153
Percentage of fair market value of share price		85.00%		85.00%
Common Stock | Restated Employee Stock Purchase Plan | Minimum
Equity, Class of Treasury Stock [Line Items]
Percentage of cash compensation paid through payroll deductions		1.00%		1.00%
Common Stock | Restated Employee Stock Purchase Plan | Maximum
Equity, Class of Treasury Stock [Line Items]
Percentage of cash compensation paid through payroll deductions		10.00%		10.00%
Common Stock | 2018 Stock Repurchase Plan
Equity, Class of Treasury Stock [Line Items]
Shares available for issuance (in shares)		1,800,000		1,800,000
Stock repurchased during period (in shares)		820,328
Stock repurchased during period		$ 25,700,000
Stock repurchased and retired (in shares)				1,488,519
Average cost per share (in dollars per share)				$ 33.58
Stock repurchased and retired				$ 50,000,000

SHARE BASED COMPENSATION - Narr

SHARE BASED COMPENSATION - Narrative (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	May 06, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise period		0 years	0 years	5 years 7 months 9 days
Options exercised intrinsic value		$ 398
Converted options from Revere acquisition (in shares)		395,298
2015 Omnibus Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized (in shares)					1,500,000
Shares available for issuance (in shares)	914,502	914,502
Expiration period		10 years
2015 Omnibus Incentive Plan | Revere acquisition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Converted options from Revere acquisition (in shares)		395,298
Weighted average grant date fair value (in dollars per share)		$ 9.14
2015 Omnibus Incentive Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage		100.00%
2015 Omnibus Incentive Plan | Stock Options and Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized compensation expense		$ 3,900	$ 2,900	$ 2,500
Options vested in period		100	200	100
2015 Omnibus Incentive Plan | Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options exercised intrinsic value		$ 400	$ 200	$ 400
Expected cost recognition weighted average period		3 months 18 days
2015 Omnibus Incentive Plan | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)		246,015
2015 Omnibus Incentive Plan | Restricted Stock | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	0		0
2015 Omnibus Incentive Plan | Restricted shares,Restricted stock units and Performance share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected cost recognition weighted average period		2 years 7 months 6 days
Unrecognized compensation expense	$ 8,000	$ 8,000
2015 Omnibus Incentive Plan | Performance Shares | 3 Year Vesting Period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)		44,905
2015 Omnibus Incentive Plan | Time Based Shares | 5 Year Vesting Period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)		201,110

SHARE BASED COMPENSATION - Fair

SHARE BASED COMPENSATION - Fair Values of all Options Granted Estimated Using Binomial Option-Pricing Model with Weighted-average Assumptions (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement [Abstract]
Dividend yield	0.00%	0.00%	2.64%
Weighted average expected volatility	0.00%	0.00%	39.13%
Weighted average risk-free interest rate	0.00%	0.00%	2.61%
Weighted average expected lives (in years)	0 years	0 years	5 years 7 months 9 days
Weighted average grant-date fair value (in dollars per share)	$ 0	$ 0	$ 11.73

SHARE BASED COMPENSATION - Summ

SHARE BASED COMPENSATION - Summary of Share Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Common Shares
Beginning balance (in shares)	65,279
Granted (in shares)	0
Converted options from Revere acquisition (in shares)	395,298
Exercised (in shares)	(26,063)	(15,080)	(20,888)
Forfeited (in shares)	(765)
Expired (in shares)	(3,711)
Ending balance (in shares)	430,038	65,279
Exercisable at period end (in shares)	425,274
Weighted Average Exercise Share Price
Beginning balance (in dollars per share)	$ 31.34
Granted (in dollars per share)	0
Converted options from Revere acquisition (in dollars per share)	12.27
Exercised (in dollars per share)	12.10
Forfeited (in dollars per share)	39.02
Expired (in dollars per share)	30.46
Ending balance (in dollars per share)	14.97	$ 31.34
Exercisable at period end (in dollars per share)	$ 14.71
Weighted Average Contractual Remaining Life (Years)
Balance at end of period	3 years
Exercisable at end of period	3 years
Aggregate Intrinsic Value (in thousands)
Beginning balance	$ 485
Exercised	398
Ending balance	6,828	$ 485
Exercisable at period end	$ 6,828

SHARE BASED COMPENSATION - Su_2

SHARE BASED COMPENSATION - Summary of Activity for Company's Restricted Stock (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Weighted Average Grant-Date Fair Value
Granted (in dollars per share)	$ 0	$ 0	$ 11.73
Restricted Stock
Number of Common Shares
Restricted stock beginning balance (in shares)	226,502
Granted (in shares)	246,015
Vested (in shares)	(66,533)
Forfeited (in shares)	(14,301)
Restricted stock ending balance (in shares)	391,683	226,502
Weighted Average Grant-Date Fair Value
Restricted stock beginning balance (in dollars per share)	$ 35.43
Granted (in dollars per share)	25.82
Vested (in dollars per share)	34.38
Forfeited (in dollars per share)	37.47
Restricted stock ending balance (in dollars per share)	$ 29.50	$ 35.43

PENSION, PROFIT SHARING, AND _3

PENSION, PROFIT SHARING, AND OTHER EMPLOYEE BENEFIT PLANS - Narrative (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	4.75%	5.00%	5.00%
Maximum percentage of asset allocated to control market volatility	70.00%
Maximum percentage of market value for initial acquisition of equity portion	5.00%
Minimum percentage of value of equity portion for sale	10.00%
Maximum percentage of corporate debt issuable to single issuer	10.00%
Contributions by employer	$ 0	$ 185
Profit sharing and matching contribution	5,300	4,100	$ 2,800
Executive incentive retirement plan benefit cost	$ 600	$ 500	$ 400

PENSION, PROFIT SHARING, AND _4

PENSION, PROFIT SHARING, AND OTHER EMPLOYEE BENEFIT PLANS - Plan's funded status (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Projected Benefit Obligation:
Projected obligation at beginning of period	$ 45,497	$ 40,152
Interest cost	1,437	1,609	$ 1,540
Actuarial loss	290	371
Benefit payments	(1,470)	(1,695)
Increase related to change in assumptions	6,672	5,060
Projected obligation at period end	52,426	45,497	40,152
Reconciliation of Fair Value of Plan Assets:
Fair value of plan assets at beginning period	43,457	37,772
Actual return on plan assets	6,370	7,195
Contribution	0	185
Benefit payments	(1,470)	(1,695)
Fair value of plan assets at end of period	48,357	43,457	37,772
Funded status at period end	(4,069)	(2,040)
Accumulated benefit obligation at period end	52,426	45,497
Unrecognized net actuarial loss	12,719	11,177	12,352
Net periodic pension cost not yet recognized	$ 12,719	$ 11,177	$ 12,352

PENSION, PROFIT SHARING, AND _5

PENSION, PROFIT SHARING, AND OTHER EMPLOYEE BENEFIT PLANS - Weighted Average Assumptions Used to Determine Benefit Obligations (Detail)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Discount rate	2.50%	3.25%	4.15%

PENSION, PROFIT SHARING, AND _6

PENSION, PROFIT SHARING, AND OTHER EMPLOYEE BENEFIT PLANS - Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Interest cost on projected benefit obligation	$ 1,437	$ 1,609	$ 1,540
Expected return on plan assets	(1,821)	(1,647)	(1,861)
Recognized net actuarial loss	874	1,059	1,000
Net periodic benefit cost	$ 490	$ 1,021	$ 679

PENSION, PROFIT SHARING, AND _7

PENSION, PROFIT SHARING, AND OTHER EMPLOYEE BENEFIT PLANS - Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Discount rate	3.25%	4.15%	3.65%
Expected return on plan assets	4.75%	5.00%	5.00%

PENSION, PROFIT SHARING, AND _8

PENSION, PROFIT SHARING, AND OTHER EMPLOYEE BENEFIT PLANS - Components of Net Unrecognized Benefits Costs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Included in accumulated other comprehensive income (loss), beginning balance	$ 11,177	$ 12,352	$ 12,487
Additions/(Reductions) during the year	(4,256)	(5,176)	3,914
Reclassifications due to recognition as net periodic pension cost	(874)	(1,059)	(1,000)
Increase (decrease) related to change in discount rate assumption	6,672	5,060	(3,049)
Included in accumulated other comprehensive income (loss), ending balance	12,719	$ 11,177	$ 12,352
Applicable tax effect	(3,249)
Included in accumulated other comprehensive income (loss), net of tax effect	9,470
Amount expected to be recognized as part of net periodic pension cost in the next fiscal year	$ 931

PENSION, PROFIT SHARING, AND _9

PENSION, PROFIT SHARING, AND OTHER EMPLOYEE BENEFIT PLANS - Component of Net Periodic Benefit (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Net actuarial loss	$ 12,719	$ 11,177	$ 12,352
Net periodic pension cost not yet recognized	$ 12,719	$ 11,177	$ 12,352

PENSION, PROFIT SHARING, AND_10

PENSION, PROFIT SHARING, AND OTHER EMPLOYEE BENEFIT PLANS - Company's pension plan weighted average (Detail)	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	100.00%	100.00%
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	11.60%	10.40%
Mutual Fund
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	88.40%	89.60%

PENSION, PROFIT SHARING, AND_11

PENSION, PROFIT SHARING, AND OTHER EMPLOYEE BENEFIT PLANS - Fair values of Company's pension plan assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	$ 48,357	$ 43,457	$ 37,772
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	14,686	11,518
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	33,671	31,939
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	0	0
Mutual Fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	48,357	43,457
Mutual Fund | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	14,686	11,518
Mutual Fund | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	33,671	31,939
Mutual Fund | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	0	0
Large cap U.S. equity funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	3,322	2,774
Large cap U.S. equity funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	2,779	1,855
Large cap U.S. equity funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	543	919
Large cap U.S. equity funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	0	0
Small/Mid cap U.S. equity funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	1,124	847
Small/Mid cap U.S. equity funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	0	0
Small/Mid cap U.S. equity funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	1,124	847
Small/Mid cap U.S. equity funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	0	0
International equity funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	1,183	894
International equity funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	1,183	894
International equity funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	0	0
International equity funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	0	0
Short-term fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	4,299	3,688
Short-term fixed income funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	0	0
Short-term fixed income funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	4,299	3,688
Short-term fixed income funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	0	0
Fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	38,429	35,254
Fixed income funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	10,724	8,769
Fixed income funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	27,705	26,485
Fixed income funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, asset category	$ 0	$ 0

PENSION, PROFIT SHARING, AND_12

PENSION, PROFIT SHARING, AND OTHER EMPLOYEE BENEFIT PLANS - Benefit payments, which reflect expected future service (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Retirement Benefits [Abstract]
2021	$ 3,340
2022	2,590
2023	2,190
2024	3,260
2025	2,410
Thereafter	$ 15,270

OTHER NON-INTEREST INCOME AND_3

OTHER NON-INTEREST INCOME AND OTHER NON-INTEREST EXPENSE - Selected Components of Other Non-Interest Income And Other Non-Interest Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Income and Expenses [Abstract]
Letter of credit fees	$ 710	$ 389	$ 611
Extension fees	1,967	1,287	873
Swap fee income	1,607	1,932	0
Loan prepayment penalties	961	404	594
Other income	3,976	4,768	5,048
Other income	9,221	8,780	7,126
Postage and delivery	1,624	1,502	1,439
Communications	2,729	2,414	2,610
Loss on FHLB redemption	5,928	0	0
Mortgage processing expense, net	1,381	817	53
Online services	1,591	1,375	1,263
Provision for credit losses on unfunded loan commitments	1,576	0	0
Franchise taxes	1,574	1,307	2,143
Insurance	1,311	1,113	1,043
Card transaction expense	1,083	1,031	961
Office supplies	912	957	951
Other expenses	10,894	9,910	9,029
Other expenses	$ 30,603	$ 20,426	$ 19,492

INCOME TAXES - Components of in

INCOME TAXES - Components of income tax expense (benefit) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current income taxes:
Federal									$ 43,115	$ 28,404	$ 18,615
State									13,785	6,598	7,183
Total current									56,900	35,002	25,798
Deferred income taxes:
Federal									(22,793)	234	4,808
State									(6,636)	1,192	1,218
Total deferred									(29,429)	1,426	6,026
Total income tax expense	$ 18,227	$ 14,292	$ (5,348)	$ 300	$ 8,614	$ 9,531	$ 8,945	$ 9,338	$ 27,471	$ 36,428	$ 31,824

INCOME TAXES - Deferred Tax Ass

INCOME TAXES - Deferred Tax Assets And Liabilities (Detail) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Allowance for credit losses	$ 42,231,000	$ 14,287,000
Lease liability	19,192,000	19,616,000
Fair value acquisition adjustments	0	1,322,000
Employee benefits	6,108,000	4,535,000
Unrealized losses on pension plan	3,249,000	2,845,000
Deferred loan fees and costs	4,486,000	471,000
Equity based compensation	1,856,000	659,000
Losses on other real estate owned	203,000	201,000
Other than temporary impairment	75,000	76,000
Loan and deposit premium/discount	1,081,000	1,422,000
Reserve for recourse loans	546,000	166,000
Net operating loss carryforward	1,475,000	916,000
Other	181,000	159,000
Gross deferred tax assets	80,683,000	46,675,000
Valuation allowance	(1,479,000)	(880,000)
Net deferred tax asset	79,204,000	45,795,000
Deferred tax liabilities:
Right of use asset	(16,693,000)	(17,688,000)
Unrealized gains on investments available-for-sale	(9,684,000)	(1,379,000)
Pension plan costs	(2,211,000)	(2,373,000)
Depreciation	(2,950,000)	(2,744,000)
Intangible assets	(6,894,000)	(3,338,000)
Bond accretion	(195,000)	(322,000)
Section 481 adjustments	(669,000)	(1,335,000)
Fair value acquisition adjustments	(555,000)	0
Other	(567,000)	(585,000)
Gross deferred tax liabilities	(40,418,000)	(29,764,000)
Net deferred tax asset	$ 38,786,000	$ 16,031,000

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 1,475				$ 916				$ 1,475	$ 916
Income tax expense (benefit)	18,227	$ 14,292	$ (5,348)	$ 300	$ 8,614	$ 9,531	$ 8,945	$ 9,338	27,471	$ 36,428	$ 31,824
Operating Loss Carryover [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance	19,900								19,900
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 23,000								23,000
WashingtonFirst Bankshares Inc | CARES Act
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)									$ (1,800)

INCOME TAXES - Reconcilements B

INCOME TAXES - Reconcilements Between Statutory Federal Income Tax Rate And Effective Tax Rate (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income tax expense at federal statutory rate									$ 26,130	$ 32,101	$ 27,865
Income tax expense at federal statutory rate									21.00%	21.00%	21.00%
Increase/ (decrease) resulting from:
Tax exempt income, net									$ (2,472)	$ (2,101)	$ (2,427)
Bank-owned life insurance									(567)	(665)	(909)
State income taxes, net of federal income tax benefits									5,648	6,154	6,637
Federal tax law change									(1,764)	0	0
Other, net									496	939	658
Total income tax expense	$ 18,227	$ 14,292	$ (5,348)	$ 300	$ 8,614	$ 9,531	$ 8,945	$ 9,338	$ 27,471	$ 36,428	$ 31,824
Increase/ (decrease) resulting from:
Tax exempt income, net									(2.00%)	(1.40%)	(1.80%)
Bank-owned life insurance									(0.50%)	(0.40%)	(0.70%)
State income taxes, net of federal income tax benefits									4.50%	4.00%	5.00%
Federal tax law change									(1.40%)	0.00%	0.00%
Other, net									0.50%	0.60%	0.50%
Total income tax expense and rate									22.10%	23.80%	24.00%

NET INCOME PER COMMON SHARE - C

NET INCOME PER COMMON SHARE - Calculation of Net Income per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net income	$ 56,662	$ 44,642	$ (14,338)	$ 9,987	$ 28,457	$ 29,383	$ 28,276	$ 30,317	$ 96,953	$ 116,433	$ 100,864
Distributed and undistributed earnings allocated to participating securities									(783)	(762)	(579)
Net income attributable to common shareholders									$ 96,170	$ 115,671	$ 100,285
Total weighted average outstanding shares (in shares)									44,312	35,797	35,707
Less: weighted average participating securities (in shares)									(365)	(235)	(205)
Basic weighted average common shares (in shares)									43,947	35,562	35,502
Dilutive common stock equivalents									185	56	21
Diluted weighted average common shares (in shares)									44,132	35,618	35,523
Basic net income per common share (in dollars per share)	$ 1.19	$ 0.94	$ (0.31)	$ 0.29	$ 0.80	$ 0.82	$ 0.79	$ 0.85	$ 2.19	$ 3.25	$ 2.82
Diluted net income per common share (in dollars per share)	$ 1.19	$ 0.94	$ (0.31)	$ 0.28	$ 0.80	$ 0.82	$ 0.79	$ 0.85	$ 2.18	$ 3.25	$ 2.82
Anti-dilutive shares (in shares)									17	9	7

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) - Net Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ (4,332,000)
Period change, net of tax	23,037,000	$ 11,422,000	$ (7,420,000)
Ending Balance	18,705,000	(4,332,000)
Unrealized Gains/ (Losses) on Investments Available-for-Sale
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	4,000,000	(6,630,000)	687,000
Period change, net of tax	24,175,000	10,630,000	(7,465,000)
Reclassification of tax effects from other comprehensive income			148,000
Ending Balance	28,175,000	4,000,000	(6,630,000)
Defined Benefit Pension Plan
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(8,332,000)	(9,124,000)	(7,544,000)
Period change, net of tax	(1,138,000)	792,000	45,000
Reclassification of tax effects from other comprehensive income			(1,625,000)
Ending Balance	(9,470,000)	(8,332,000)	(9,124,000)
Total
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(4,332,000)	(15,754,000)	(6,857,000)
Period change, net of tax	23,037,000	11,422,000	(7,420,000)
Reclassification of tax effects from other comprehensive income			(1,477,000)
Ending Balance	$ 18,705,000	$ (4,332,000)	$ (15,754,000)

ACCUMULATED OTHER COMPREHENSI_4

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) - Reclassification Adjustments Out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Unrealized gains/(losses) on investments available-for-sale Affected line item in the Statements of Income:
Investment securities gains	$ 467	$ 77	$ 190
Income before taxes	467	77	190
Tax expense	120	20	50
Net income	347	57	140
Amortization of defined benefit pension plan items Affected line item in the Statements of Income:
Recognized actuarial loss	(874)	(1,059)	(1,000)
Income before taxes	(874)	(1,059)	(1,000)
Tax benefit	(223)	(277)	(261)
Net loss	$ (651)	$ (782)	$ (739)

DERIVATIVES - Interest Rate Swa

DERIVATIVES - Interest Rate Swaps (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Pay fixed/receive variable swaps
Derivatives, Fair Value [Line Items]
Notional Amount	$ 160,261	$ 102,337
Estimated Fair Value	$ (9,183)	$ (2,507)
Years to Maturity	8 years 8 months 12 days	9 years 1 month 6 days
Receive Rate	2.39%	3.40%
Pay Rate	3.72%	4.11%
Pay variable/receive fixed swaps
Derivatives, Fair Value [Line Items]
Notional Amount	$ 160,261	$ 102,337
Estimated Fair Value	$ 9,183	$ 2,507
Years to Maturity	8 years 8 months 12 days	9 years 1 month 6 days
Receive Rate	3.72%	4.11%
Pay Rate	2.39%	3.40%
Total swaps
Derivatives, Fair Value [Line Items]
Notional Amount	$ 320,522	$ 204,674
Estimated Fair Value	$ 0	$ 0
Years to Maturity	8 years 8 months 12 days	9 years 1 month 6 days
Receive Rate	3.06%	3.76%
Pay Rate	3.06%	3.76%

FINANCIAL INSTRUMENTS WITH OF_3

FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK - Summary Of Financial Instruments With Off-Balance Sheet Credit Risk (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Commitments to extend credit and available credit lines	$ 3,320,157	$ 2,196,977
Commercial real estate development and construction
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Commitments to extend credit and available credit lines	871,290	571,368
Residential real estate-development and construction
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Commitments to extend credit and available credit lines	94,096	89,224
Real estate-residential mortgage
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Commitments to extend credit and available credit lines	335,288	74,282
Lines of credit, principally home equity and business lines
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Commitments to extend credit and available credit lines	1,947,706	1,400,038
Standby letters of credit
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total Commitments to extend credit and available credit lines	$ 71,777	$ 62,065

FINANCIAL INSTRUMENTS WITH OF_4

FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Financial Information Disclosure [Abstract]
Provision for credit losses on unfunded loan commitments	$ 1,576	$ 0	$ 0

FAIR VALUE - Financial Assets a

FAIR VALUE - Financial Assets and Liabilities at Dates Indicated that Were Accounted for or Disclosed at Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Residential mortgage loans held for sale (at fair value)	$ 78,294	$ 53,701
Investments available-for-sale (at fair value)	1,348,021	1,073,333
Residential mortgage loans held for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Residential mortgage loans held for sale (at fair value)	75,500	52,600
Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	1,348,021	1,073,333
Total assets	1,435,498	1,129,541
Total liabilities	(9,183)	(2,507)
Fair Value, Measurements, Recurring | Residential mortgage loans held for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Residential mortgage loans held for sale (at fair value)	78,294	53,701
Fair Value, Measurements, Recurring | U.S. treasuries and government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	43,297	258,495
Fair Value, Measurements, Recurring | State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	390,367	233,649
Fair Value, Measurements, Recurring | Mortgage-backed and asset-backed
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	904,432	570,759
Fair Value, Measurements, Recurring | Corporate debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	9,925	9,552
Fair Value, Measurements, Recurring | Trust preferred
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		310
Fair Value, Measurements, Recurring | Marketable equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		568
Fair Value, Measurements, Recurring | Total swaps
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap agreements	9,183	2,507
Interest rate swap agreements	(9,183)	(2,507)
Fair Value, Measurements, Recurring | Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		1,072,765
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Total assets	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Residential mortgage loans held for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Residential mortgage loans held for sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. treasuries and government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage-backed and asset-backed
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Trust preferred
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Marketable equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Total swaps
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap agreements	0	0
Interest rate swap agreements	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	1,338,096	1,063,471
Total assets	1,425,573	1,119,679
Total liabilities	(9,183)	(2,507)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Residential mortgage loans held for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Residential mortgage loans held for sale (at fair value)	78,294	53,701
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. treasuries and government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	43,297	258,495
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	390,367	233,649
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Mortgage-backed and asset-backed
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	904,432	570,759
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Trust preferred
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Marketable equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		568
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Total swaps
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap agreements	9,183	2,507
Interest rate swap agreements	(9,183)	(2,507)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		1,062,903
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	9,925	9,862
Total assets	9,925	9,862
Total liabilities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Residential mortgage loans held for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Residential mortgage loans held for sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | U.S. treasuries and government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Mortgage-backed and asset-backed
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Corporate debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	9,925	9,552
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Trust preferred
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		310
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Marketable equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Total swaps
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap agreements	0	0
Interest rate swap agreements	$ 0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		$ 9,862

FAIR VALUE - Activity of assets

FAIR VALUE - Activity of assets reported as Level 3 (Detail) - Fair Value, Inputs, Level 3 - Available-for-Sale Securities $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 9,862
Transfer into Level 3 assets	0
Additions of Level 3 assets	3,050
Elimination of investments in WashingtonFirst and Revere sub debt	(3,000)
Sales of Level 3 assets	(310)
Total unrealized gains included in accumulated other comprehensive income	323
Ending balance	$ 9,925

FAIR VALUE - Assets Measured at

FAIR VALUE - Assets Measured at Fair Value on Nonrecurring Basis (Detail) - Fair Value, Nonrecurring - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	$ 15,356	$ 8,368
Fair value measured on nonrecurring basis losses	(11,612)	(6,580)
Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	13,901	6,886
Fair value measured on nonrecurring basis losses	(11,326)	(6,299)
Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	1,455	1,482
Fair value measured on nonrecurring basis losses	(286)	(281)
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	0	0
Significant Other Observable Inputs (Level 2) | Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	0	0
Significant Other Observable Inputs (Level 2) | Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	0	0
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	15,356	8,368
Significant Unobservable Inputs (Level 3) | Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	13,901	6,886
Significant Unobservable Inputs (Level 3) | Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	$ 1,455	$ 1,482

FAIR VALUE - Narrative (Detail)

FAIR VALUE - Narrative (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Balance of loans individually evaluated for credit loss	$ 97,718	$ 24,773
Fair value disclosure	86,300	19,300
Allowance related to loans evaluated individually	$ 11,405	5,501
Impaired loans		$ 24,773

FAIR VALUE - Carrying Amounts a

FAIR VALUE - Carrying Amounts and Fair Values of Company's Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financial assets:
Residential mortgage loans held for sale (at fair value)	$ 78,294	$ 53,701
Estimated Fair Value	1,348,021	1,073,333
Loans, net of allowance	10,235,142	6,649,100
Accrued interest receivable	46,431	23,282
Financial liabilities:
Time deposits	1,657,662
Other deposits	10,033,069	6,440,319
Securities sold under retail repurchase agreements and federal funds purchased	543,157	213,605
Advances from FHLB	379,075	513,777
Subordinated debt	227,088	209,406
Carrying Amount
Financial assets:
Cash and cash equivalents	297,003	146,103
Residential mortgage loans held for sale (at fair value)	78,294	53,701
Estimated Fair Value	1,348,021	1,073,333
Equity securities	65,760	51,803
Loans, net of allowance	10,235,142	6,649,100
Interest rate swap agreements	9,183	2,507
Accrued interest receivable	46,431	23,282
Bank owned life insurance	126,887	113,171
Financial liabilities:
Time deposits	1,657,662	1,542,322
Other deposits	8,375,407	4,897,997
Securities sold under retail repurchase agreements and federal funds purchased	543,157	213,605
Advances from FHLB	379,075	513,777
Subordinated debt	227,088	209,406
Interest rate swap agreements	9,183	2,507
Accrued interest payable	3,254	4,194
Estimated Fair Value
Financial assets:
Cash and cash equivalents	297,003	146,103
Residential mortgage loans held for sale (at fair value)	78,294	53,701
Estimated Fair Value	1,348,021	1,073,333
Equity securities	65,760	51,803
Loans, net of allowance	10,336,355	6,628,054
Interest rate swap agreements	9,183	2,507
Accrued interest receivable	46,431	23,282
Bank owned life insurance	126,887	113,171
Financial liabilities:
Time deposits	1,674,112	1,547,116
Other deposits	8,375,407	4,897,997
Securities sold under retail repurchase agreements and federal funds purchased	543,157	213,605
Advances from FHLB	390,593	520,729
Subordinated debt	227,512	200,864
Interest rate swap agreements	9,183	2,507
Accrued interest payable	3,254	4,194
Quoted Prices in Active Markets for Identical Assets (Level 1) | Estimated Fair Value
Financial assets:
Cash and cash equivalents	297,003	146,103
Residential mortgage loans held for sale (at fair value)	0	0
Estimated Fair Value	0	0
Equity securities	65,760	51,803
Loans, net of allowance	0	0
Interest rate swap agreements	0	0
Accrued interest receivable	46,431	23,282
Bank owned life insurance	0	0
Financial liabilities:
Time deposits	0	0
Other deposits	8,375,407	4,897,997
Securities sold under retail repurchase agreements and federal funds purchased	0	0
Advances from FHLB	0	0
Subordinated debt	0	0
Interest rate swap agreements	0	0
Accrued interest payable	3,254	4,194
Significant Other Observable Inputs (Level 2) | Estimated Fair Value
Financial assets:
Cash and cash equivalents	0	0
Residential mortgage loans held for sale (at fair value)	78,294	53,701
Estimated Fair Value	1,338,096	1,063,471
Equity securities	0	0
Loans, net of allowance	0	0
Interest rate swap agreements	9,183	2,507
Accrued interest receivable	0	0
Bank owned life insurance	126,887	113,171
Financial liabilities:
Time deposits	1,674,112	1,547,116
Other deposits	0	0
Securities sold under retail repurchase agreements and federal funds purchased	543,157	213,605
Advances from FHLB	390,593	520,729
Subordinated debt	0	0
Interest rate swap agreements	9,183	2,507
Accrued interest payable	0	0
Significant Unobservable Inputs (Level 3) | Estimated Fair Value
Financial assets:
Cash and cash equivalents	0	0
Residential mortgage loans held for sale (at fair value)	0	0
Estimated Fair Value	9,925	9,862
Equity securities	0	0
Loans, net of allowance	10,336,355	6,628,054
Interest rate swap agreements	0	0
Accrued interest receivable	0	0
Bank owned life insurance	0	0
Financial liabilities:
Time deposits	0	0
Other deposits	0	0
Securities sold under retail repurchase agreements and federal funds purchased	0	0
Advances from FHLB	0	0
Subordinated debt	227,512	200,864
Interest rate swap agreements	0	0
Accrued interest payable	$ 0	$ 0

PARENT COMPANY FINANCIAL INFO_3

PARENT COMPANY FINANCIAL INFORMATION - Statements of Condition (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 297,003	$ 146,103
Investments available-for-sale (at fair value)	1,348,021	1,073,333
Equity securities	65,760	51,803
Goodwill	370,223	347,149	$ 347,149
Other assets	265,859	216,593
Total assets	12,798,429	8,629,002	8,243,272
Liabilities
Subordinated debt	227,088	209,406
Accrued expenses and other liabilities	146,085	118,921
Total liabilities	11,328,474	7,496,028
Stockholders’ Equity:
Common stock	47,057	34,970
Additional paid-in capital	846,922	586,622
Retained earnings	557,271	515,714
Accumulated other comprehensive income/ (loss)	18,705	(4,332)
Total stockholders' equity	1,469,955	1,132,974	$ 1,067,903	$ 563,816
Total liabilities and stockholders' equity	12,798,429	8,629,002
Parent Company
Assets
Cash and cash equivalents	63,943	90,361
Investments available-for-sale (at fair value)	9,925	10,430
Equity securities	568	0
Investment in subsidiary	1,589,483	1,242,229
Goodwill	1,292	1,292
Other assets	2,684	1,480
Total assets	1,667,895	1,345,792
Liabilities
Subordinated debt	196,454	209,406
Accrued expenses and other liabilities	1,486	3,412
Total liabilities	197,940	212,818
Stockholders’ Equity:
Common stock	47,057	34,970
Additional paid-in capital	846,922	586,622
Retained earnings	557,271	515,714
Accumulated other comprehensive income/ (loss)	18,705	(4,332)
Total stockholders' equity	1,469,955	1,132,974
Total liabilities and stockholders' equity	$ 1,667,895	$ 1,345,792

PARENT COMPANY FINANCIAL INFO_4

PARENT COMPANY FINANCIAL INFORMATION - Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income:
Other income									$ 3,976	$ 4,768	$ 5,048
Expenses:
Total expenses	$ 11,964	$ 15,500	$ 13,413	$ 19,524	$ 19,807	$ 20,292	$ 21,029	$ 21,433	60,401	82,561	63,637
Income before income tax expense	74,889	58,934	(19,686)	10,287	37,071	38,914	37,221	39,655	124,424	152,861	132,688
Income tax expense (benefit)	18,227	14,292	(5,348)	300	8,614	9,531	8,945	9,338	27,471	36,428	31,824
Net income	$ 56,662	$ 44,642	$ (14,338)	$ 9,987	$ 28,457	$ 29,383	$ 28,276	$ 30,317	96,953	116,433	100,864
Parent Company
Income:
Cash dividends from subsidiary									74,410	42,625	39,370
Other income									932	1,093	897
Total income									75,342	43,718	40,267
Expenses:
Interest									9,028	3,141	1,922
Other expenses									1,505	1,507	1,135
Total expenses									10,533	4,648	3,057
Income before income tax expense									64,809	39,070	37,210
Income tax expense (benefit)									(1,988)	(734)	(283)
Income before equity in undistributed income of subsidiary									66,797	39,804	37,493
Equity in undistributed income of subsidiary									30,156	76,629	63,371
Net income									$ 96,953	$ 116,433	$ 100,864

PARENT COMPANY FINANCIAL INFO_5

PARENT COMPANY FINANCIAL INFORMATION - Statements of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows from Operating Activities:
Net income	$ 56,662	$ 44,642	$ (14,338)	$ 9,987	$ 28,457	$ 29,383	$ 28,276	$ 30,317	$ 96,953	$ 116,433	$ 100,864
Adjustments to reconcile net income to net cash provided by operating activities:
Share based compensation expense									3,850	3,042	2,645
Other-net									2,660	(721)	3,970
Net cash provided by operating activities									141,981	99,943	147,646
Cash Flows from Investing Activities:
Proceeds from sales of investment available-for-sale									(633,741)	(326,604)	(161,349)
Acquisition of business activity, net of cash paid									(26,925)	0	0
Net cash used in investing activities									(1,200,196)	(241,276)	(505,004)
Cash Flows from Financing Activities:
Retirement of subordinated debt									(10,310)	0	0
Proceeds from issuance of common stock									1,997	1,433	1,395
Stock tendered for payment of withholding taxes									(458)	(703)	(760)
Repurchase of Common Stock									(25,702)	(24,284)	0
Dividends paid									(53,175)	(42,272)	(39,277)
Net cash provided by financing activities									1,209,115	185,955	346,339
Net increase/ (decrease) in cash and cash equivalents									150,900	44,622	(11,019)
Cash and cash equivalents at beginning of year				146,103				101,481	146,103	101,481	112,500
Cash and cash equivalents at end of year	297,003				146,103				297,003	146,103	101,481
Parent Company
Cash Flows from Operating Activities:
Net income									96,953	116,433	100,864
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed income-subsidiary									(30,156)	(76,629)	(63,371)
Share based compensation expense									3,850	3,042	2,645
Tax benefit from stock options exercised									5	7	8
Other-net									(9,732)	0	(3,252)
Net cash provided by operating activities									60,920	42,853	36,894
Cash Flows from Investing Activities:
Proceeds from sales of investment available-for-sale									310	0	0
Investment in subsidiary									0	(85,000)	0
Acquisition of business activity, net of cash paid									0	0	11,845
Net cash used in investing activities									310	(85,000)	11,845
Cash Flows from Financing Activities:
Retirement of subordinated debt									(10,310)	0	0
Proceeds from issuance of subordinated debt									0	175,000	0
Proceeds from issuance of common stock									1,997	1,433	1,395
Stock tendered for payment of withholding taxes									(458)	(703)	(760)
Repurchase of Common Stock									(25,702)	(24,284)	0
Dividends paid									(53,175)	(42,272)	(39,277)
Net cash provided by financing activities									(87,648)	109,174	(38,642)
Net increase/ (decrease) in cash and cash equivalents									(26,418)	67,027	10,097
Cash and cash equivalents at beginning of year				$ 90,361				$ 23,334	90,361	23,334	13,237
Cash and cash equivalents at end of year	$ 63,943				$ 90,361				$ 63,943	$ 90,361	$ 23,334

REGULATORY MATTERS - Company's

REGULATORY MATTERS - Company's and Bank's actual capital amounts and ratios (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Company
Tier 1 Leverage:
Actual Amount, Tier One Leverage Capital	$ 1,078,213	$ 794,300
Actual Ratio, Tier One Leverage Capital	8.92%	9.70%
For Capital Adequacy Purposes Amount, Tier One Leverage Capital	$ 483,619	$ 327,577
For Capital Adequacy Purposes Ratio, Tier One Leverage Capital	4.00%	4.00%
Common Equity Tier 1 Capital to risk-
Actual Amount, Common Equity Tier 1 Capital	$ 1,078,213	$ 783,903
Actual Ratio, Common Equity Tier 1 Capital	10.58%	11.06%
For Capital Adequacy Purposes Amount, Common Equity Tier 1 Capital	$ 458,612	$ 318,860
For Capital Adequacy Purposes Ratio, Common Equity Tier 1 Capital	4.50%	4.50%
Tier 1 Capital to risk-weighted assets:
Actual Amount, Tier One Risk Based Capital	$ 1,078,213	$ 794,300
Actual Ratio, Tier One Risk Based Capital	10.58%	11.21%
For Capital Adequacy Purposes Amount, Tier One Risk Based Capital	$ 611,483	$ 425,147
For Capital Adequacy Purposes Ratio, Tier One Risk Based Capital	6.00%	6.00%
Total Capital to risk-weighted assets:
Actual Amount, Capital	$ 1,419,973	$ 1,052,328
Actual Ratio, Capital	13.93%	14.85%
For Capital Adequacy Purposes Amount, Capital	$ 815,311	$ 566,863
For Capital Adequacy Purposes Ratio, Capital	8.00%	8.00%
Sandy Spring Bank
Tier 1 Leverage:
Actual Amount, Tier One Leverage Capital	$ 1,199,570	$ 894,659
Actual Ratio, Tier One Leverage Capital	9.93%	10.94%
For Capital Adequacy Purposes Amount, Tier One Leverage Capital	$ 483,175	$ 327,123
For Capital Adequacy Purposes Ratio, Tier One Leverage Capital	4.00%	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions Amount, Tier One Leverage Capital	$ 603,969	$ 408,904
To Be Well Capitalized Under Prompt Action Provisions Ratio, Tier One Leverage Capital	5.00%	5.00%
Common Equity Tier 1 Capital to risk-
Actual Amount, Common Equity Tier 1 Capital	$ 1,199,570	$ 894,659
Actual Ratio, Common Equity Tier 1 Capital	11.79%	12.65%
For Capital Adequacy Purposes Amount, Common Equity Tier 1 Capital	$ 457,920	$ 318,259
For Capital Adequacy Purposes Ratio, Common Equity Tier 1 Capital	4.50%	4.50%
To Be Well Capitalized Under Prompt Corrective Action Provisions Amount, Common Equity Tier 1 Capital	$ 661,441	$ 459,708
To Be Well Capitalized Under Prompt Action Provisions Ratio, Common Equity Tier 1 Capital	6.50%	6.50%
Tier 1 Capital to risk-weighted assets:
Actual Amount, Tier One Risk Based Capital	$ 1,199,570	$ 894,659
Actual Ratio, Tier One Risk Based Capital	11.79%	12.65%
For Capital Adequacy Purposes Amount, Tier One Risk Based Capital	$ 610,561	$ 424,346
For Capital Adequacy Purposes Ratio, Tier One Risk Based Capital	6.00%	6.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions Amount, Tier One Risk Based Capital	$ 814,081	$ 565,794
To Be Well Capitalized Under Prompt Action Provisions Ratio, Tier One Risk Based Capital	8.00%	8.00%
Total Capital to risk-weighted assets:
Actual Amount, Capital	$ 1,347,102	$ 950,793
Actual Ratio, Capital	13.24%	13.44%
For Capital Adequacy Purposes Amount, Capital	$ 814,081	$ 565,794
For Capital Adequacy Purposes Ratio, Capital	8.00%	8.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions Amount, Capital	$ 1,017,601	$ 707,243
To Be Well Capitalized Under Prompt Action Provisions Ratio, Capital	10.00%	10.00%

SEGMENT REPORTING - Narrative (

SEGMENT REPORTING - Narrative (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)segment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment	3
Amortization of intangible assets	$ 6,221	$ 1,946	$ 2,162
Community Banking
Segment Reporting Information [Line Items]
Amortization of intangible assets	4,300	1,700	1,900
Insurance
Segment Reporting Information [Line Items]
Amortization of intangible assets	100	100	100
Investment Management
Segment Reporting Information [Line Items]
Amortization of intangible assets	1,900	$ 100	$ 100
Assets under management	$ 3,400,000

SEGMENT REPORTING - Operating S

SEGMENT REPORTING - Operating Segments and Reconciliation of Information to Condensed Consolidated Financial Statements (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Interest income	$ 111,791	$ 112,984	$ 114,927	$ 83,858	$ 85,390	$ 87,082	$ 87,214	$ 88,183	$ 423,560	$ 347,869	$ 324,082
Interest expense	11,964	15,500	13,413	19,524	19,807	20,292	21,029	21,433	60,401	82,561	63,637
Provision for credit losses	(4,489)	7,003	58,686	24,469	1,655	1,524	1,633	(128)	85,669	4,684	9,023
Non-interest income	32,234	29,390	22,924	18,168	19,224	18,573	16,556	16,969	102,716	71,322	61,049
Non-interest expenses	61,661	60,937	85,438	47,746	46,081	44,925	43,887	44,192	255,782	179,085	179,783
Income before income tax expense	74,889	58,934	(19,686)	10,287	37,071	38,914	37,221	39,655	124,424	152,861	132,688
Income tax expense	18,227	14,292	(5,348)	300	8,614	9,531	8,945	9,338	27,471	36,428	31,824
Net income	56,662	$ 44,642	$ (14,338)	$ 9,987	28,457	$ 29,383	$ 28,276	$ 30,317	96,953	116,433	100,864
Assets	12,798,429				8,629,002				12,798,429	8,629,002	8,243,272
Inter-Segment Elimination
Segment Reporting Information [Line Items]
Interest income									(13)	(37)	(10)
Interest expense									(13)	(37)	(10)
Provision for credit losses									0	0	0
Non-interest income									(865)	(667)	(615)
Non-interest expenses									(865)	(667)	(615)
Income before income tax expense									0	0	0
Income tax expense									0	0	0
Net income									0	0	0
Assets	(71,211)				(22,352)				(71,211)	(22,352)	(28,507)
Community Banking | Operating Segments
Segment Reporting Information [Line Items]
Interest income									423,560	347,867	324,081
Interest expense									60,414	82,598	63,647
Provision for credit losses									85,669	4,684	9,023
Non-interest income									78,940	55,042	45,841
Non-interest expenses									237,910	166,802	168,261
Income before income tax expense									118,507	148,825	128,991
Income tax expense									25,907	35,350	30,827
Net income									92,600	113,475	98,164
Assets	12,800,537				8,624,590				12,800,537	8,624,590	8,246,282
Insurance | Operating Segments
Segment Reporting Information [Line Items]
Interest income									6	26	3
Interest expense									0	0	0
Provision for credit losses									0	0	0
Non-interest income									6,810	6,621	6,153
Non-interest expenses									5,686	5,731	5,601
Income before income tax expense									1,130	916	555
Income tax expense									313	258	169
Net income									817	658	386
Assets	11,335				10,340				11,335	10,340	9,165
Investment Management | Operating Segments
Segment Reporting Information [Line Items]
Interest income									7	13	8
Interest expense									0	0	0
Provision for credit losses									0	0	0
Non-interest income									17,831	10,326	9,670
Non-interest expenses									13,051	7,219	6,536
Income before income tax expense									4,787	3,120	3,142
Income tax expense									1,251	820	828
Net income									3,536	2,300	2,314
Assets	$ 57,768				$ 16,424				$ 57,768	$ 16,424	$ 16,332

QUARTERLY FINANCIAL INFORMATION

QUARTERLY FINANCIAL INFORMATION (Unaudited) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Interest income	$ 111,791	$ 112,984	$ 114,927	$ 83,858	$ 85,390	$ 87,082	$ 87,214	$ 88,183	$ 423,560	$ 347,869	$ 324,082
Interest expense	11,964	15,500	13,413	19,524	19,807	20,292	21,029	21,433	60,401	82,561	63,637
Net interest income	99,827	97,484	101,514	64,334	65,583	66,790	66,185	66,750	363,159	265,308	260,445
Provision/ (credit) for credit losses	(4,489)	7,003	58,686	24,469	1,655	1,524	1,633	(128)	85,669	4,684	9,023
Non-interest income	32,234	29,390	22,924	18,168	19,224	18,573	16,556	16,969	102,716	71,322	61,049
Non-interest expenses	61,661	60,937	85,438	47,746	46,081	44,925	43,887	44,192	255,782	179,085	179,783
Income before income taxes and equity in undistributed income of subsidiary	74,889	58,934	(19,686)	10,287	37,071	38,914	37,221	39,655	124,424	152,861	132,688
Income tax expense	18,227	14,292	(5,348)	300	8,614	9,531	8,945	9,338	27,471	36,428	31,824
Net income	$ 56,662	$ 44,642	$ (14,338)	$ 9,987	$ 28,457	$ 29,383	$ 28,276	$ 30,317	$ 96,953	$ 116,433	$ 100,864
Basic net income per common share (in dollars per share)	$ 1.19	$ 0.94	$ (0.31)	$ 0.29	$ 0.80	$ 0.82	$ 0.79	$ 0.85	$ 2.19	$ 3.25	$ 2.82
Diluted net income per common share (in dollars per share)	$ 1.19	$ 0.94	$ (0.31)	$ 0.28	$ 0.80	$ 0.82	$ 0.79	$ 0.85	$ 2.18	$ 3.25	$ 2.82