ACQUISITIONS (Details 1) (Central Bankcorp, Inc. [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Central Bankcorp, Inc. [Member]
Business Acquisition [Line Items]
Net interest income after provision for loan losses	$ 165,860	$ 170,514
Net income	$ 47,261	$ 46,477