CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Impact of CECL Adoption	[1]	Common Stock	Additional Paid-in Capital	Accumulated Retained Earnings	Accumulated Retained Earnings Impact of CECL Adoption	[1]	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2018	$ 1,969,697			$ 617	$ 1,674,274	$ 300,407			$ (5,601)
Balance (in shares) at Dec. 31, 2018				62,480,755
Increase (Decrease) in Stockholders' Equity
Net income	118,620					118,620
Other comprehensive income	35,796								35,796
Repurchase and retirement of common stock	(100,000)			$ (33)	(89,887)	(10,080)
Repurchase and retirement of common stock (in shares)				(3,364,761)
Cash dividends declared	(40,807)					(40,807)
Dividend equivalents declared	0				89	(89)
Share-based compensation expense	7,927				7,927
Issuance of restricted stock, net	0
Issuance of restricted stock, net (in shares)				316,254
Restricted stock surrendered and canceled	(2,629)				(2,629)
Restricted stock surrendered and canceled (in shares)				(111,456)
Exercise of stock options	394				394
Exercise of stock options (in shares)				43,548
Balance at Sep. 30, 2019	1,988,998			$ 584	1,590,168	368,051			30,195
Balance (in shares) at Sep. 30, 2019				59,364,340
Balance at Dec. 31, 2018	1,969,697			$ 617	1,674,274	300,407			(5,601)
Balance (in shares) at Dec. 31, 2018				62,480,755
Balance at Dec. 31, 2019	$ 2,012,594	$ (45,625)		$ 586	1,594,434	396,051	$ (45,625)		21,523
Balance (in shares) at Dec. 31, 2019	59,506,057			59,506,057
Increase (Decrease) in Stockholders' Equity
Accounting standards update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Balance at Jun. 30, 2019	$ 1,984,456			$ 595	1,618,137	343,366			22,358
Balance (in shares) at Jun. 30, 2019				60,509,994
Increase (Decrease) in Stockholders' Equity
Net income	41,375					41,375
Other comprehensive income	7,837								7,837
Repurchase and retirement of common stock	(34,031)			$ (11)	(30,634)	(3,386)
Repurchase and retirement of common stock (in shares)				(1,145,515)
Cash dividends declared	(13,266)					(13,266)
Dividend equivalents declared	0				38	(38)
Share-based compensation expense	2,614				2,614
Issuance of restricted stock, net	0
Issuance of restricted stock, net (in shares)				11,500
Restricted stock surrendered and canceled	0
Restricted stock surrendered and canceled (in shares)				(12,250)
Exercise of stock options	13				13
Exercise of stock options (in shares)				611
Balance at Sep. 30, 2019	1,988,998			$ 584	1,590,168	368,051			30,195
Balance (in shares) at Sep. 30, 2019				59,364,340
Balance at Dec. 31, 2019	$ 2,012,594	$ (45,625)		$ 586	1,594,434	396,051	$ (45,625)		21,523
Balance (in shares) at Dec. 31, 2019	59,506,057			59,506,057
Increase (Decrease) in Stockholders' Equity
Net income	$ (6,785)					(6,785)
Other comprehensive income	24,140								24,140
Cash dividends declared	(53,464)					(53,464)
Dividend equivalents declared	0				217	(217)
Share-based compensation expense	7,747				7,747
Issuance of restricted stock, net	0
Issuance of restricted stock, net (in shares)				493,411
Issuance of common stock - acquisition	749,603			$ 344	749,259
Issuance of common stock - acquisition (in shares)				34,407,403
Restricted stock surrendered and canceled	(1,372)				(1,372)
Restricted stock surrendered and canceled (in shares)				(102,486)
Exercise of stock options	1,247				1,247
Exercise of stock options (in shares)				71,136
Balance at Sep. 30, 2020	$ 2,688,085			$ 930	2,351,532	289,960			45,663
Balance (in shares) at Sep. 30, 2020	94,375,521			94,375,521
Balance at Jun. 30, 2020	$ 2,654,647			$ 930	2,348,415	247,078			58,224
Balance (in shares) at Jun. 30, 2020				94,350,902
Increase (Decrease) in Stockholders' Equity
Net income	66,566					66,566
Other comprehensive income	(12,561)								(12,561)
Cash dividends declared	(23,590)					(23,590)
Dividend equivalents declared	0				94	(94)
Share-based compensation expense	2,899				2,899
Issuance of restricted stock, net	0
Issuance of restricted stock, net (in shares)				19,902
Issuance of common stock - acquisition	0
Issuance of common stock - acquisition (in shares)				0
Restricted stock surrendered and canceled	(99)				(99)
Restricted stock surrendered and canceled (in shares)				(8,180)
Exercise of stock options	223				223
Exercise of stock options (in shares)				12,897
Balance at Sep. 30, 2020	$ 2,688,085			$ 930	$ 2,351,532	$ 289,960			$ 45,663
Balance (in shares) at Sep. 30, 2020	94,375,521			94,375,521

[1] Related to the adoption of Accounting Standards Update 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. See Note 2 - Recently Issue Accounting Pronouncements for further discussion.