Cover - shares	3 Months Ended
	Mar. 31, 2024	Apr. 30, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	0-19065
Entity Registrant Name	SANDY SPRING BANCORP, INC.
Entity Incorporation State Country Code	MD
Entity Tax Identification Number	52-1532952
Entity Address Address Line1	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
Security 12b Title	Common Stock, par value $1.00 per share
Trading Symbol	SASR
Security Exchange Name	NASDAQ
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
Entity Shell Company	false
Entity Common Stock Shares Outstanding (in shares)		45,061,353
Amendment Flag	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Entity Central Index Key	0000824410
Current Fiscal Year End Date	--12-31