Employee Benefit Plans - Additional Information (Detail) - USD ($)				1 Months Ended	3 Months Ended	12 Months Ended
	May 24, 2023	Feb. 25, 2021	Nov. 18, 2015	May 31, 2023	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Apr. 22, 2021	Aug. 20, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Benefits bases on years of service and compensation, years						5 years
Number of equity shares						55,300	55,300
Contribution of pension fund						$ 0	$ 0	$ 0
Eligible employee contributions specified percentage one						3.00%	3.00%	3.00%
Eligible employee contributions specified percentage two						2.00%	2.00%	2.00%
Eligibility percentage of employee contributions						100.00%	100.00%	100.00%
Eligibility percentage of employee contributions						50.00%	50.00%	50.00%
Stock options granted to selected participants						154,600
Stock options granted to selected participants exercise price per share						$ 24.91
Total intrinsic value of options exercised						$ 100,000	$ 1,000,000
Cash received from stock option exercised						200,000	3,000,000
Tax benefit realized from stock options exercised						20,000	300,000
Total intrinsic value of the outstanding shares						1,700,000
Total intrinsic value of the shares exercisable						800,000
Assets						17,712,374,000	16,931,905,000
Shareholder Return Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total expense for the KSOP/Compensation expense for the stock option component of the Plan						$ 300,000	200,000	$ 400,000
Expense recognition period						2 years
Number of shares granted						12,000
Restricted shares vesting period			3 years
Percentage of shares earned by participants			200.00%
Total shareholder return measurement period			3 years
Grant date fair value						$ 33.47
Total unrecognized compensation expense						$ 600,000
Scenario Forecast [Member] | Shareholder Return Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted					12,000
Shares Vested in 2024 [Member] | Scenario Forecast [Member] | Shareholder Return Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share vested					4,000
Shares Vested in 2025 [Member] | Scenario Forecast [Member] | Shareholder Return Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share vested					4,000
Shares Vested in 2026 [Member] | Scenario Forecast [Member] | Shareholder Return Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share vested					4,000
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Assets						15,000,000,000	15,000,000,000
key Officers [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense for Annual Bonus						$ 4,400,000	4,400,000	3,500,000
401(k) Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares held by KSOP						472,910
Total expense for the KSOP/Compensation expense for the stock option component of the Plan						$ 5,900,000	$ 5,500,000	5,300,000
Future issuance under equity compensation plans						65,270	165,438
Equity Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Future issuance under equity compensation plans						1,069,689	1,468,140
Additional common stock for issuance									2,000,000
Selected Participants Including Certain Executive Officers [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted to selected participants	154,600
Stock options granted to selected participants exercise price per share	$ 24.91
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total expense for the KSOP/Compensation expense for the stock option component of the Plan						$ 900,000	$ 1,100,000	800,000
Options grant expired						7 years
Total unrecognized compensation expense related to non-vested stock option grants						$ 400,000
Expense recognition period						1 year
Employee Stock Option | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options grant expired						10 years
Service Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted						236,038
Fair value of restricted stock granted						$ 25.02
Service Based Restricted Stock [Member] | 79616 Cliff Vesting [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares vesting period						36 months
Performance Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted						37,224
Restricted shares vesting period						3 years
Performance Based Restricted Stock [Member] | Vesting on May 18, 2026 after the Completion of the Three-year Performance Period [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage						50.00%
Performance Based Restricted Stock [Member] | Vesting on May 18, 2027 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage						50.00%
Performance Based Restricted Stock [Member] | Maximum [Member] | National Peer Group of Financial Institutions [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Assets						$ 29,200,000,000
Performance Based Restricted Stock [Member] | Minimum [Member] | National Peer Group of Financial Institutions [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Assets						$ 13,500,000,000
2018 Performance Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pro-rata award achieved, percentage		75.00%
Number of share vested				2,492
2018 Performance Based Restricted Stock [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pro-rata award achieved, percentage		99.00%
2018 Performance Based Restricted Stock [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pro-rata award achieved, percentage		75.00%
2019 Performance Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted						4,550
Performance targets achieved, percentage							85.00%
2020 Performance Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted						8,584
Performance targets achieved, percentage							85.00%
2021 Performance Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted						5,547
Performance targets achieved, percentage							75.00%
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total expense for the KSOP/Compensation expense for the stock option component of the Plan						$ 5,900,000	$ 5,000,000	$ 5,600,000
Expense recognition period						1 year 7 months 6 days
Number of shares granted						273,262
Fair value of restricted stock granted						$ 25.01
Total unrecognized compensation expense related to non-vested restricted stock grants						$ 9,300,000
Number of share vested						206,274
Grant date fair value						$ 28.85	$ 28.67
Farmers Capital Bank Corporation [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Postretirement medical benefit plan										$ 15,000,000.0
Defined benefit plan, Unrealized gain						$ 5,500,000
Life of the plan						17 years
Defined Benefit Plan, Equity Securities, Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock fair market value						$ 1,700,000	$ 2,000,000