COMMITMENTS AND CONTINGENCIES AND OTHER MATTERS (Details 2) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Other
Securities sold under agreements to repurchase	$ 36,263,000	$ 11,370,000
Bridgehampton National Bank
Other
Required cash balance with Federal Reserve Bank of New York	1,000,000
Average balance maintained	9,800,000
Amount available for transactions under Master Repurchase Agreement	686,500,000
Securities sold under agreements to repurchase	36,300,000
Bridgehampton National Bank | Overnight line of credit with the Federal Home Loan Bank of New York
Other
Lines of credit with unaffiliated correspondent banks to provide short-term credit	295,000,000
Lines of credit available on an unsecured basis	275,000,000
Lines of credit outstanding	$ 75,000,000