Statements of Income/(Loss) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income:
Other income	$ 3,140	$ 2,515	$ 2,816
Expenses:
Total expenses	22,651	26,524	32,742
Income (loss) before income taxes and equity in undistributed income (loss) of subsidiary	54,599	49,947	32,569
Income tax benefit	18,045	15,845	9,049
Net income	36,554	34,102	23,520
Preferred stock dividends and discount accretion	0	0	6,149
Net income (loss) available to common shareholders	36,554	34,102	17,371
Sandy Spring Bancorp, Inc
Income:
Cash dividends from subsidiary	12,028	21,339	0
Other income	982	945	1,191
Total income	13,010	22,284	1,191
Expenses:
Interest	959	913	940
Other expenses	1,003	784	911
Total expenses	1,962	1,697	1,851
Income (loss) before income taxes and equity in undistributed income (loss) of subsidiary	11,048	20,587	(660)
Income tax benefit	(221)	(210)	(167)
Income (loss) before equity in undistributed income (loss) of subsidiary	11,269	20,797	(493)
Equity in undistributed (excess distributions) income (loss) of subsidiary	25,285	13,305	24,013
Net income	36,554	34,102	23,520
Preferred stock dividends and discount accretion	0	0	6,149
Net income (loss) available to common shareholders	$ 36,554	$ 34,102	$ 17,371