Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	COMMON STOCK	ADDITIONAL PAID-IN CAPITAL	RETAINED EARNINGS	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	TREASURYSTOCK	UNALLOCATED ESOP SHARES	COMMON STOCK ACQUIRED BY DEFERRED COMP PLANS	DEFERRED COMPENSATION PLANS
Beginning Balance at Dec. 31, 2020	$ 1,619,797	$ 832	$ 962,453	$ 718,090	$ 17,655	$ (59,018)	$ (20,215)	$ (4,549)	$ 4,549
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	48,559			48,559
Other comprehensive loss, net of tax	(4,678)				(4,678)
Cash dividends paid	(18,075)			(18,075)
Distributions from DDFP	28		28					168	(168)
Purchases of treasury stock	(48)					(48)
Purchase of employee restricted shares to fund statutory tax withholding	(915)					(915)
Shares issued dividend reinvestment plan	0
Stock option exercises	638		(82)			720
Allocation of ESOP shares	913		145				768
Allocation of Stock Award Plan ("SAP") shares	959		959
Allocation of stock options	53		53
Ending Balance at Mar. 31, 2021	1,647,231	832	963,556	748,574	12,977	(59,261)	(19,447)	(4,381)	4,381
Beginning Balance at Dec. 31, 2021	1,697,096	832	969,815	814,533	6,863	(79,603)	(15,344)	(3,984)	3,984
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	43,962			43,962
Other comprehensive loss, net of tax	(74,809)				(74,809)
Cash dividends paid	(18,688)			(18,688)
Distributions from DDFP	45		45					140	(140)
Purchases of treasury stock	(29,025)					(29,025)
Purchase of employee restricted shares to fund statutory tax withholding	(953)					(953)
Shares issued dividend reinvestment plan	0
Stock option exercises	0
Allocation of ESOP shares	1,143		332				811
Allocation of Stock Award Plan ("SAP") shares	2,311		2,311
Allocation of stock options	49		49
Ending Balance at Mar. 31, 2022	$ 1,621,131	$ 832	$ 972,552	$ 839,807	$ (67,946)	$ (109,581)	$ (14,533)	$ (3,844)	$ 3,844