Employee Benefit Plans - Components of and Weighted-Average Assumptions Used in Determining Net Periodic Benefit Costs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Components of net periodic benefit cost:
Service cost—benefits earned during year	$ 1,418	$ 2,190	$ 2,500
Interest cost on projected benefit obligation	6,304	4,114	3,416
Expected return on plan assets	$ (11,154)	$ (11,572)	$ (11,207)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Employee Benefits	Employee Benefits	Employee Benefits
Amortization of prior service credit	$ (34)	$ (34)	$ (34)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Employee Benefits	Employee Benefits	Employee Benefits
Amortization of net loss	$ 903	$ 506	$ 2,736
Net periodic pension income	(2,563)	(4,796)	(2,589)
Other changes in plan assets and benefit obligations recognized in other comprehensive income:
Net gain for the period	(8,592)	4,353	(16,290)
Amortization of prior service credit	34	34	34
Amortization of net loss	(903)	(505)	(2,736)
Total recognized in other comprehensive loss (income)	(9,461)	3,882	(18,992)
Total recognized in net periodic pension cost and other comprehensive income	$ (12,024)	$ (914)	$ (21,581)
Weighted-average assumptions used to determine net periodic pension cost:
Discount rate	5.23%	3.03%	2.74%
Rate of compensation increase	3.84%	3.62%	3.30%
Expected long-term return on assets	6.82%	5.74%	6.11%
Farmers Capital Bank Corporation Postretirement Medical Benefit Plan [Member]
Components of net periodic benefit cost:
Interest cost on projected benefit obligation	$ 332	$ 266
Amortization of prior service credit	(224)	(224)
Amortization of net loss	(245)	43
Net periodic pension income	(137)	85
Other changes in plan assets and benefit obligations recognized in other comprehensive income:
Net gain for the period	(316)	(3,881)
Amortization of prior service credit	224	224
Amortization of net loss	245	(43)
Total recognized in other comprehensive loss (income)	153	(3,700)
Total recognized in net periodic pension cost and other comprehensive income	$ 16	$ (3,615)
Weighted-average assumptions used to determine net periodic pension cost:
Discount rate	4.93%	5.10%