Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock, at Cost	Accumulated Other Comprehensive Income (Loss)	Unearned Compensation - ESOP	Total
Balance at beginning of period at Dec. 31, 2019	$ 584	$ 460,232	$ 237,356	$ (721)	$ 1,480	$ (33,137)	$ 665,794
Balance, beginning of period (in shares) at Dec. 31, 2019	58,418,021
Comprehensive income (loss)			27,192		296		27,488
Dividends declared per share			(3,244)				(3,244)
ESOP shares committed to be released		156				1,378	1,534
Restricted stock awards forfeited (in shares)	(8,679)
Share-based compensation expense		3,143					3,143
Treasury stock purchased				(612)			(612)
Treasury stock purchased (in shares)	(66,878)
Balance at end of period at Sep. 30, 2020	$ 584	463,531	261,304	(1,333)	1,776	(31,759)	694,103
Balance, end of period (in shares) at Sep. 30, 2020	58,342,464
Balance at beginning of period at Jun. 30, 2020	$ 584	462,881	251,032	(721)	2,897	(32,218)	684,455
Balance, beginning of period (in shares) at Jun. 30, 2020	58,418,021
Comprehensive income (loss)			11,893		(1,121)		10,772
Dividends declared per share			(1,621)				(1,621)
ESOP shares committed to be released		33				459	492
Restricted stock awards forfeited (in shares)	(8,679)
Share-based compensation expense		617					617
Treasury stock purchased				(612)			(612)
Treasury stock purchased (in shares)	(66,878)
Balance at end of period at Sep. 30, 2020	$ 584	463,531	261,304	(1,333)	1,776	(31,759)	694,103
Balance, end of period (in shares) at Sep. 30, 2020	58,342,464
Balance at beginning of period at Dec. 31, 2020	$ 584	464,176	277,312	(16,644)	2,185	(31,299)	$ 696,314
Balance, beginning of period (in shares) at Dec. 31, 2020	57,205,458						57,205,458
Comprehensive income (loss)			45,927		(3,303)		$ 42,624
Dividends declared per share			(7,556)				(7,556)
ESOP shares committed to be released		955				1,378	2,333
Restricted stock awards granted (in shares)	185,377
Share-based compensation expense		2,753					2,753
Stock option exercised	$ 1	642					643
Stock option exercised (in shares)	62,840
Treasury stock purchased				(57,079)			(57,079)
Treasury stock purchased (in shares)	(4,221,565)
Balance at end of period at Sep. 30, 2021	$ 585	468,526	315,683	(73,723)	(1,118)	(29,921)	$ 680,032
Balance, end of period (in shares) at Sep. 30, 2021	53,232,110						53,232,110
Balance at beginning of period at Jun. 30, 2021	$ 585	467,194	305,831	(38,588)	829	(30,380)	$ 705,471
Balance, beginning of period (in shares) at Jun. 30, 2021	55,735,623
Comprehensive income (loss)			12,259		(1,947)		10,312
Dividends declared per share			(2,407)				(2,407)
ESOP shares committed to be released		340				459	799
Restricted stock awards forfeited (in shares)	(3,000)
Share-based compensation expense		992					992
Treasury stock purchased				(35,135)			(35,135)
Treasury stock purchased (in shares)	(2,500,513)
Balance at end of period at Sep. 30, 2021	$ 585	$ 468,526	$ 315,683	$ (73,723)	$ (1,118)	$ (29,921)	$ 680,032
Balance, end of period (in shares) at Sep. 30, 2021	53,232,110						53,232,110