Parent Company Financial Information (Statements of Income) (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income:
Other income									$ 4,219,000	$ 5,260,000	$ 3,140,000
Expenses:
Total interest expense	4,748,000	4,730,000	4,682,000	4,658,000	4,759,000	4,874,000	4,847,000	4,953,000	18,818,000	19,433,000	22,651,000
Income before income taxes	13,234,000	16,570,000	9,704,000	16,274,000	14,118,000	18,508,000	18,515,000	15,844,000	55,782,000	66,985,000	54,599,000
Income Tax Expense (Benefit)	(4,086,000)	(5,428,000)	(2,722,000)	(5,346,000)	(4,505,000)	(6,419,000)	(6,353,000)	(5,286,000)	(17,582,000)	(22,563,000)	(18,045,000)
Net income	9,148,000	11,142,000	6,982,000	10,928,000	9,613,000	12,089,000	12,162,000	10,558,000	38,200,000	44,422,000	36,554,000
Sandy Spring Bancorp, Inc
Income:
Cash dividends from subsidiary									19,530,000	16,585,000	12,028,000
Other income									902,000	931,000	982,000
Total income									20,432,000	17,516,000	13,010,000
Expenses:
Interest									881,000	895,000	959,000
Other expenses									1,060,000	1,044,000	1,003,000
Total interest expense									1,941,000	1,939,000	1,962,000
Income before income taxes									18,491,000	15,577,000	11,048,000
Income Tax Expense (Benefit)									(266,000)	(271,000)	(221,000)
Income before equity in undistributed income of subsidiary									18,757,000	15,848,000	11,269,000
Equity in undistributed income of subsidiary									19,443,000	28,574,000	25,285,000
Net income									$ 38,200,000	$ 44,422,000	$ 36,554,000