ACQUISITIONS (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended							12 Months Ended
	Feb. 20, 2015	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Nov. 10, 2016
Business Acquisition [Line Items]
Acquisition Related Costs		$ 4,764	$ 151	$ 206	$ 334	$ 0	$ 271	$ 10,230	$ 5,455	$ 10,501	$ 1,339
New England Bancorp, Inc. [Member]
Business Acquisition [Line Items]
Number of shares of company stock issued for each share of Central common stock (in shares)												0.25
Value of shares of company stock issued for each share of acquiree stock (in dollars per share)												$ 15.14
Company's closing price per share (in dollars per share)												$ 60.55
Business transaction value												$ 41,700
Increase in acquirer outstanding shares												672,665
Acquisition Related Costs									5,000
Loans acquired												$ 225,731
Combination of INDB and New England Bancorp, Inc. [Member]
Business Acquisition [Line Items]
Acquisition Related Costs									6,300
Peoples Federal Bancshares, Inc [Member]
Business Acquisition [Line Items]
Equity Interest Issued or Issuable Shareholders Option To Receive, Cash Per Share	$ 21.00
Number of shares of company stock issued for each share of Central common stock (in shares)	0.5523
Value of shares of company stock issued for each share of acquiree stock (in dollars per share)	$ 23.26
Company's closing price per share (in dollars per share)	$ 42.11
Business transaction value	$ 141,800
Cost of acquired entity, percentage cash	40.00%
Business Acquisition, Cost of Acquired Entity, Percentage Stock Consideration	60.00%
Cost of acquired entity, cash paid	$ 55,400
Consideration Transferred, Equity Interests Issued and Issuable	$ 86,400
Increase in acquirer outstanding shares	2,052,137
Acquisition Related Costs									$ 10,500
Loans acquired	$ 463,927
Combination of INDB and Peoples Federal Bancshares, Inc [Member]
Business Acquisition [Line Items]
Acquisition Related Costs										$ 16,700