Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Aug. 07, 2019
Document and entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Entity Registrant Name	SANDY SPRING BANCORP, INC.
Entity Central Index Key	0000824410
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock Shares Outstanding		35,618,558
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Ex Transition Period	false
Security 12b Title	Common Stock, par value $1.00 per share
Trading Symbol	SASR
Security Exchange Name	NASDAQ
Entity File Number	0-19065
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
Document Quarterly Report	true
Document Transition Report	false