CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Preferred stock	Common stock	Additional paid-in capital	Unearned compensation	Retained earnings (deficit)	Accumulated other comprehensive income/(loss)	Treasury stock	Preferred stock Preferred stock	Common stock Common stock	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjustment Retained earnings (deficit)
Balance at beginning of period (in shares) at Dec. 31, 2018		522	45,417
Balance at beginning of period at Dec. 31, 2018	$ 1,552,918	$ 40,633	$ 460	$ 1,245,013	$ (6,594)	$ 308,839	$ (13,470)	$ (21,963)
Comprehensive income (loss)
Net income (loss)	71,699					71,699
Other comprehensive income (loss)	29,350						29,350
Total comprehensive income (loss)	101,049					71,699	29,350
Acquisition of SI Financial Group, Inc. (in shares)			5,691
Acquisition of SI Financial Group, Inc.	176,711		$ 57	176,654
Cash dividends declared on common shares	(32,756)					(32,756)
Cash dividends declared on preferred shares	(720)					(720)
Treasury shares repurchased (in shares)			(910)
Treasury shares repurchased	(27,651)							(27,651)
Forfeited shares (in shares)			(59)
Forfeited shares				(234)	1,951			(1,717)
Exercise of stock options (in shares)			6
Exercise of stock options	69					(89)		158
Restricted stock grants (in shares)			284
Restricted stock grants				869	(8,372)			7,503
Stock-based compensation	3,546				3,546
Other, net (in shares)			(35)
Other, net	(942)			51		(2)		(991)
Balance at end of period (in shares) at Sep. 30, 2019		522	50,394
Balance at end of period at Sep. 30, 2019	1,772,224	$ 40,633	$ 517	1,422,353	(9,469)	346,971	15,880	(44,661)
Balance at beginning of period (in shares) at Dec. 31, 2018		522	45,417
Balance at beginning of period at Dec. 31, 2018	1,552,918	$ 40,633	$ 460	1,245,013	(6,594)	308,839	(13,470)	(21,963)
Balance at end of period (in shares) at Dec. 31, 2019		522	49,585
Balance at end of period at Dec. 31, 2019	$ 1,758,564	$ 40,633	$ 517	1,422,441	(8,465)	361,082	11,993	(69,637)			$ (24,380)	$ (24,380)
Comprehensive income (loss)
Accounting standards update	us-gaap:AccountingStandardsUpdate201613Member
Balance at beginning of period (in shares) at Jun. 30, 2019		522	51,045
Balance at beginning of period at Jun. 30, 2019	$ 1,779,837	$ 40,633	$ 517	1,421,461	(6,555)	336,542	11,301	(24,062)
Comprehensive income (loss)
Net income (loss)	22,616					22,616
Other comprehensive income (loss)	4,579						4,579
Total comprehensive income (loss)	27,195					22,616	4,579
Cash dividends declared on common shares	(11,812)					(11,812)
Cash dividends declared on preferred shares	(240)					(240)
Treasury shares repurchased (in shares)			(800)
Treasury shares repurchased	(24,325)							(24,325)
Forfeited shares (in shares)			(8)
Forfeited shares				(25)	252			(227)
Exercise of stock options (in shares)			5
Exercise of stock options	55					(74)		129
Restricted stock grants (in shares)			152
Restricted stock grants				867	(4,709)			3,842
Stock-based compensation	1,543				1,543
Other, net (in shares)			0
Other, net	(29)			50		(61)		(18)
Balance at end of period (in shares) at Sep. 30, 2019		522	50,394
Balance at end of period at Sep. 30, 2019	1,772,224	$ 40,633	$ 517	1,422,353	(9,469)	346,971	15,880	(44,661)
Balance at beginning of period (in shares) at Dec. 31, 2019		522	49,585
Balance at beginning of period at Dec. 31, 2019	1,758,564	$ 40,633	$ 517	1,422,441	(8,465)	361,082	11,993	(69,637)			$ (24,380)	$ (24,380)
Comprehensive income (loss)
Net income (loss)	(548,026)					(548,026)
Other comprehensive income (loss)	20,433						20,433
Total comprehensive income (loss)	(527,593)					(548,026)	20,433
Conversion of preferred stock to common stock (in shares)									(261)	522
Conversion of preferred stock to common stock	0			5,391				14,911	$ (20,308)	$ 6
Cash dividends declared on common shares	(30,143)					(30,143)
Cash dividends declared on preferred shares	(313)					(313)
Treasury shares repurchased (in shares)			(14)
Treasury shares repurchased	(473)							(473)
Forfeited shares (in shares)			(87)
Forfeited shares				(1,551)	2,648			(1,097)
Exercise of stock options (in shares)			33
Exercise of stock options	607					(395)		1,002
Restricted stock grants (in shares)			306
Restricted stock grants				(3,981)	(5,159)			9,140
Stock-based compensation	3,450				3,450
Other, net (in shares)			(39)
Other, net	(694)			0		0		(694)
Balance at end of period (in shares) at Sep. 30, 2020		261	50,306
Balance at end of period at Sep. 30, 2020	1,179,025	$ 20,325	$ 523	1,422,300	(7,526)	(242,175)	32,426	(46,848)
Balance at beginning of period (in shares) at Jun. 30, 2020		261	50,192
Balance at beginning of period at Jun. 30, 2020	1,164,140	$ 20,325	$ 523	1,427,728	(8,298)	(257,352)	33,239	(52,025)
Comprehensive income (loss)
Net income (loss)	21,225					21,225
Other comprehensive income (loss)	(813)						(813)
Total comprehensive income (loss)	20,412					21,225	(813)
Cash dividends declared on common shares	(5,993)					(5,993)
Cash dividends declared on preferred shares	(58)					(58)
Forfeited shares (in shares)			(74)
Forfeited shares				(1,395)	2,163			(768)
Exercise of stock options (in shares)			0
Exercise of stock options	0					0		0
Restricted stock grants (in shares)			198
Restricted stock grants				(4,033)	(2,026)			6,059
Stock-based compensation	635				635
Other, net (in shares)			(10)
Other, net	(111)					3		(114)
Balance at end of period (in shares) at Sep. 30, 2020		261	50,306
Balance at end of period at Sep. 30, 2020	$ 1,179,025	$ 20,325	$ 523	$ 1,422,300	$ (7,526)	$ (242,175)	$ 32,426	$ (46,848)