CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Acquisition of Legacy Bancorp, Inc.	Acquisition of Rome Bancorp, Inc.	Acquisition of The Connecticut Bank and Trust Company	Common stock	Common stock Acquisition of Legacy Bancorp, Inc.	Common stock Acquisition of Rome Bancorp, Inc.	Common stock Acquisition of The Connecticut Bank and Trust Company	Additional paid-in capital	Additional paid-in capital Acquisition of Legacy Bancorp, Inc.	Additional paid-in capital Acquisition of Rome Bancorp, Inc.	Additional paid-in capital Acquisition of The Connecticut Bank and Trust Company	Unearned compensation	Retained earnings	Accumulated other comprehensive loss	Treasury stock	Comprehensive income
Balance at Dec. 31, 2010	$ 388,647				$ 158				$ 337,537				$ (1,776)	$ 103,972	$ (6,410)	$ (44,834)
Balance (in shares) at Dec. 31, 2010					14,076
Comprehensive income:
Net income	9,104													9,104			9,104
Other net comprehensive income	870														870		870
Total comprehensive income	9,974																9,974
Acquisitions		101,683	55,490			44	27			101,639	55,463
Acquisitions (in shares)						4,351	2,661
Rome ESOP loan repayment	(943)															(943)
Rome ESOP loan repayment (in shares)					(44)
Cash dividends declared $0.51 and $0.48 for nine months ended September 30, 2012 and 2011, respectively	(8,313)													(8,313)
Forfeited shares									40				463			(503)
Forfeited shares (in shares)					(23)
Exercise of stock options	214													(112)		326
Exercise of stock options (in shares)					13
Restricted stock grants									(404)				(2,730)			3,134
Restricted stock grants (in shares)					125
Stock-based compensation	998								2				996
Net tax benefit related to stock-based compensation	68								68
Other, net	(1,125)								(249)					(364)		(512)
Other, net (in shares)					(25)
Balance at Sep. 30, 2011	546,693				229				494,096				(3,047)	104,287	(5,540)	(43,332)
Balance (in shares) at Sep. 30, 2011					21,134
Balance at Dec. 31, 2011	553,365				229				494,304				(2,790)	109,477	(4,885)	(42,970)
Balance (in shares) at Dec. 31, 2011					21,148
Comprehensive income:
Net income	23,859													23,859			23,859
Other net comprehensive income	1,423														1,423		1,423
Total comprehensive income	25,282																25,282
Acquisitions				21,990				9				21,981
Acquisitions (in shares)								965
Cash dividends declared $0.51 and $0.48 for nine months ended September 30, 2012 and 2011, respectively	(11,147)													(11,147)
Forfeited shares									11				169			(180)
Forfeited shares (in shares)					(8)
Exercise of stock options	376													(82)		458
Exercise of stock options (in shares)					18
Restricted stock grants									(280)				(2,434)			2,714
Restricted stock grants (in shares)					108
Stock-based compensation	1,410												1,410
Net tax benefit related to stock-based compensation	40								40
Other, net	(395)															(395)
Other, net (in shares)					(18)
Balance at Sep. 30, 2012	$ 590,921				$ 238				$ 516,056				$ (3,645)	$ 122,107	$ (3,462)	$ (40,373)
Balance (in shares) at Sep. 30, 2012					22,213