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 Connecticut Bank and Trust Company	Acquisition of Beacon Federal Bancorp, Inc	Common stock	Common stock Acquisition of Legacy Bancorp, Inc.	Common stock Acquisition of Rome Bancorp, Inc.	Common stock Acquisition of Connecticut Bank and Trust Company	Common stock Acquisition of Beacon Federal Bancorp, Inc	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 Connecticut Bank and Trust Company	Additional paid-in capital Acquisition of Beacon Federal Bancorp, Inc	Unearned compensation	Retained earnings	Accumulated other comprehensive income (loss)	Treasury stock	Comprehensive income
Balance at Dec. 31, 2009	$ 384,067					$ 158					$ 338,822					$ (1,318)	$ 98,519	$ (2,968)	$ (49,146)
Balance (in shares) at Dec. 31, 2009						13,916
Comprehensive income:
Net income	13,615																13,615			13,615
Other net comprehensive income (loss)	(3,442)																	(3,442)		(3,442)
Total comprehensive income	10,173																			10,173
Cash dividends declared $0.69, $0.65 and $0.64 for the year ended December 31, 2012, 2011 and 2010, respectively	(8,989)																(8,989)
Forfeited shares											3					268			(271)
Forfeited shares (in shares)						(14)
Exercise of stock options	1,004																(513)		1,517
Exercise of stock options (in shares)						60
Restricted stock grants											(1,199)					(2,322)			3,521
Restricted stock grants (in shares)						139
Stock-based compensation	1,601										5					1,596
Net tax expense related to stock-based compensation	(94)										(94)
Other, net	(439)																16		(455)
Other, net (in shares)						(25)
Balance at Dec. 31, 2010	387,323					158					337,537					(1,776)	102,648	(6,410)	(44,834)
Balance (in shares) at Dec. 31, 2010						14,076
Comprehensive income:
Net income	17,348																17,348			17,348
Other net comprehensive income (loss)	1,525																	1,525		1,525
Total comprehensive income	18,873																			18,873
Acquisition		101,683	55,490				44	27				101,639	55,463
Acquisition (in shares)							4,351	2,661
Employee Stock Ownership Plan	(943)																		(943)
Employee Stock Ownership Plan (in shares)						(44)
Cash dividends declared $0.69, $0.65 and $0.64 for the year ended December 31, 2012, 2011 and 2010, respectively	(11,910)																(11,910)
Forfeited shares											40					463			(503)
Forfeited shares (in shares)						(23)
Exercise of stock options	252																(166)		418
Exercise of stock options (in shares)						16
Restricted stock grants											(474)					(2,925)			3,399
Restricted stock grants (in shares)						160
Stock-based compensation	1,450										3					1,447
Net tax expense related to stock-based compensation	68										68
Other, net	(478)										28					1			(507)
Other, net (in shares)						(49)
Balance at Dec. 31, 2011	551,808					229					494,304					(2,790)	107,920	(4,885)	(42,970)
Balance (in shares) at Dec. 31, 2011						21,148
Comprehensive income:
Net income	33,188																33,188			33,188
Other net comprehensive income (loss)	1,906																	1,906		1,906
Total comprehensive income	35,094																			35,094
Acquisition				21,990	68,005				9	27				21,981	67,978
Acquisition (in shares)									965	2,700
Cash dividends declared $0.69, $0.65 and $0.64 for the year ended December 31, 2012, 2011 and 2010, respectively	(15,634)																(15,634)
Forfeited shares											11					169			(180)
Forfeited shares (in shares)						(8)
Exercise of stock options	3,044																(3,460)		6,504
Exercise of stock options (in shares)						254
Restricted stock grants											(280)					(2,434)			2,714
Restricted stock grants (in shares)						108
Stock-based compensation	2,260										240					2,020
Net tax expense related to stock-based compensation	1,126										1,126
Other, net	(428)																		(428)
Other, net (in shares)						(19)
Balance at Dec. 31, 2012	$ 667,265					$ 265					$ 585,360					$ (3,035)	$ 122,014	$ (2,979)	$ (34,360)
Balance (in shares) at Dec. 31, 2012						25,148