Parent Company Financial Information (Statements of Cash Flows) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash Flows from Operating Activities:
Net income	$ 38,200,000	$ 44,422,000	$ 36,554,000
Adjustments to reconcile net income to net cash provided by operating activities:
Share based compensation expense	1,452,000	1,688,000	1,451,000
Net change in other liabilities	20,166,000	(5,965,000)	6,939,000
Other-net	(4,997,000)	13,046,000	3,954,000
Net cash provided by operating activities	53,664,000	96,142,000	52,790,000
Cash Flows from Investing Activities:
Purchase of investment available-for-sale	0	(161,379,000)	(264,993,000)
Acquistion of business activity, net of cash acquired	0	0	(849,000)
Net cash used in investing activities	(262,337,000)	(233,190,000)	(56,565,000)
Cash Flows from Financing Activities:
Redemption of stock warrant	(910,000)	0	0
Proceeds from issuance of common stock	394,000	153,000	98,000
Tax benefit from stock options exercised	321,000	0	102,000
Dividends paid	(19,216,000)	(16,130,000)	(11,891,000)
Net cash provided by financing activities	230,463,000	125,069,000	17,867,000
Net increase (decrease) in cash and cash equivalents	21,790,000	(11,979,000)	14,092,000
Cash and cash equivalents at beginning of period	74,427,000	86,406,000	72,314,000
Cash and cash equivalents at end of period	96,217,000	74,427,000	86,406,000
Sandy Spring Bancorp, Inc
Cash Flows from Operating Activities:
Net income	38,200,000	44,422,000	36,554,000
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed income-subsidiary	(19,443,000)	(28,574,000)	(25,285,000)
Share based compensation expense	1,452,000	1,688,000	1,451,000
Net change in other liabilities	(185,000)	(44,000)	(158,000)
Decrease in dividends receivable	0	0	13,000,000
Other-net	(76,000)	1,000	(10,804,000)
Net cash provided by operating activities	19,948,000	17,493,000	14,758,000
Cash Flows from Investing Activities:
Purchase of investment available-for-sale	0	0	(511,000)
Acquistion of business activity, net of cash acquired	0	0	(849,000)
Net cash used in investing activities	0	0	(1,360,000)
Cash Flows from Financing Activities:
Proceeds from issuance of common stock	394,000	153,000	99,000
Tax benefit from stock options exercised	321,000	0	102,000
Repurchase of common stock	(910,000)	0	0
Dividends paid	(19,216,000)	(16,130,000)	(11,890,000)
Net cash provided by financing activities	(19,411,000)	(15,977,000)	(11,689,000)
Net increase (decrease) in cash and cash equivalents	537,000	1,516,000	1,709,000
Cash and cash equivalents at beginning of period	11,551,000	10,035,000	8,326,000
Cash and cash equivalents at end of period	$ 12,088,000	$ 11,551,000	$ 10,035,000