CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Retained Earnings	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	38,718			38,718
Other comprehensive income	10,661				10,661
Cash dividends declared	(13,749)			(13,749)
Dividend equivalents declared	0		13	(13)
Share-based compensation expense	2,453		2,453
Issuance of restricted stock, net	0
Issuance of restricted stock, net (in shares)		289,754
Restricted stock surrendered and canceled	(1,047)		(1,047)
Restricted stock surrendered and canceled (in shares)		(37,279)
Exercise of stock options	331		331
Exercise of stock options (in shares)		40,069
Balance at Mar. 31, 2019	2,007,064	$ 617	1,676,024	325,363	5,060
Balance (in shares) at Mar. 31, 2019		62,773,299
Balance at Dec. 31, 2019	$ 2,012,594	$ 586	1,594,434	396,051	21,523
Balance (in shares) at Dec. 31, 2019	59,506,057	59,506,057
Increase (Decrease) in Stockholders' Equity
Net income	$ 25,740			25,740
Other comprehensive income	22,886				22,886
Cash dividends declared	(14,882)			(14,882)
Dividend equivalents declared	0		42	(42)
Share-based compensation expense	2,309		2,309
Issuance of restricted stock, net	0
Issuance of restricted stock, net (in shares)		446,815
Restricted stock surrendered and canceled	(1,008)		(1,008)
Restricted stock surrendered and canceled (in shares)		(29,474)
Exercise of stock options	903		903
Exercise of stock options (in shares)		51,883
Balance at Mar. 31, 2020	$ 2,002,917	$ 586	$ 1,596,680	$ 361,242	$ 44,409
Balance (in shares) at Mar. 31, 2020	59,975,281	59,975,281