Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2021 USD ($) Contract Office Fee RevenueCategory	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of offices | Office	180
Percentage of outstanding principal to be repurchased under GNMA optional repurchase program	100.00%
Number of days to pass to be classified as past due LHFI	30 days
Finite-lived intangible assets, average useful life	20 years
Securities with limited marketability	$ 32,900,000	$ 31,700,000
Other-than-temporary impairment of investment in member bank stock	$ 0	0	$ 0
Number of types of interchange fees | Fee	2
Other real estate sales, net (losses) gains	$ (1,869,000)	897,000	$ (291,000)
Number of trust management revenue categories | RevenueCategory	5
Time period between service obligation completed and payment received from trust customer	30 days
Increase to allowance for credit loss on off-balance sheet credit exposures	$ 0	$ 29,638,000
Fisher Brown Bottrell Insurance, Inc. [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of general categories of insurance contracts | Contract	4
Credit Card Loans [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days past due loans are to be charged-off	180 days
Commercial Credits [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days past due for loan to be classified as nonaccrual	90 days
Non-Business Purpose Credits [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days past due for loan to be classified as nonaccrual	120 days
Number of days past due loans are to be charged-off	120 days
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days mortgage LHFS are retained on balance sheet	30 days
Minimum [Member] | Fisher Brown Bottrell Insurance, Inc. [Member] | Personal Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Insurance contracts payment received period	30 days
Minimum [Member] | Fisher Brown Bottrell Insurance, Inc. [Member] | Employee Benefits Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Insurance contracts payment received period	60 days
Minimum [Member] | Furniture and Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets	3 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days mortgage LHFS are retained on balance sheet	45 days
Maximum [Member] | Fisher Brown Bottrell Insurance, Inc. [Member] | Personal Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Insurance contracts payment received period	60 days
Maximum [Member] | Fisher Brown Bottrell Insurance, Inc. [Member] | Employee Benefits Insurance Contracts [Member]
Summary Of Significant Accounting Policies [Line Items]
Insurance contracts payment received period	90 days
Maximum [Member] | Buildings [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets	39 years
Maximum [Member] | Furniture and Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets	10 years
Maximum [Member] | 1-4 Family Residential Real Estate [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days past due loans are to be charged-off	180 days
ASU 2016-13 [Member] | Securities Available for Sale [Member]
Summary Of Significant Accounting Policies [Line Items]
Current expected credit loss	$ 0
ASU 2019-12 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2021
Change in accounting principle, accounting standards update, adopted [true false]	true
Change in accounting principle, accounting standards update, immaterial effect [true false]	true
ASU 2018-14 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2021
Change in accounting principle, accounting standards update, adopted [true false]	true
Change in accounting principle, accounting standards update, immaterial effect [true false]	true
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Summary Of Significant Accounting Policies [Line Items]
Description of variable rate basis for derivative	three-month LIBOR
Period for which cash flow hedges will be used to hedge quarterly interest payments	5 years
Derivative inception date	Dec. 31, 2014
Derivative maturity date	Dec. 31, 2019