Basis of Accounting and Consolidation - Additional Information (Details) - USD ($)				3 Months Ended		12 Months Ended	47 Months Ended
	Feb. 14, 2022	Sep. 10, 2021	Feb. 22, 2021	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Mar. 31, 2022	Jul. 28, 2021	Sep. 25, 2020
Summary Of Significant Accounting Policies [Line Items]
Common stock, par value (in dollars per share)				$ 4	$ 4		$ 4
Assets				$ 6,632,006,000		$ 5,986,582,000	$ 6,632,006,000
Loans				4,394,050,000		3,938,120,000	4,394,050,000
Deposits		$ 215,000,000		$ 5,487,305,000		$ 4,956,486,000	$ 5,487,305,000
Loans acquired		208,000,000
Core deposit intangible asset		$ 4,900,000
Amortization period		10 years
Stock plans, term				10 years
Maximum number of shares to be issued in stock incentive plan (in shares)				399,983			399,983
Employee discount for employee stock purchase plan				15.00%
Employee stock purchase plan, number of shares authorized				600,000			600,000
Stock issued during period, shares, employee stock purchase plans				3,149	3,142		34,833
Captive maximum gross premiums				$ 2,450,000
Stock Options
Summary Of Significant Accounting Policies [Line Items]
Common stock awarded in SI plan (in shares)				0
Restricted Stock
Summary Of Significant Accounting Policies [Line Items]
Common stock awarded in SI plan (in shares)				26,000		13,175
Restricted Stock Units (RSUs)
Summary Of Significant Accounting Policies [Line Items]
Common stock awarded in SI plan (in shares)				37,150		35,400
Delta Bancshares Company
Summary Of Significant Accounting Policies [Line Items]
Percentage of issued and outstanding shares acquired								100.00%
Common stock, par value (in dollars per share)								$ 10.00
Share Price								$ 4.00
Consideration payable in cash	$ 15,150,000
Consideration payable in shares	2,292,270
Assets				$ 748,000,000			$ 748,000,000
Loans				434,000,000			434,000,000
Deposits				$ 561,000,000			$ 561,000,000
LINCO Bancshares, Inc.
Summary Of Significant Accounting Policies [Line Items]
Percentage of issued and outstanding shares acquired									100.00%
Common stock, par value (in dollars per share)									$ 1.00
Share Price									$ 4.00
Consideration payable in cash			$ 103,500,000
Consideration payable in shares			1,262,246
Dividends			$ 13,000,000