DOCUMENT AND ENTITY INFORMATION - $ / shares	9 Months Ended
	Sep. 30, 2018	Nov. 06, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Trading Symbol	SASR
Entity Common Stock, Shares Outstanding		35,523,703
Entity Listing, Par Value Per Share	$ 1
Entity Registrant Name	SANDY SPRING BANCORP INC
Entity Central Index Key	0000824410
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer