Employee Benefit Plans - Additional Information (Detail) - USD ($)			12 Months Ended
	May 15, 2019	Nov. 15, 2015	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	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
Maximum amount of pension plan invested			5.00%
Maximum common stock percentage of market value of investee			5.00%
Maximum percentage of investment in bonds or notes			5.00%
Maximum period for invested in bonds or notes issued			20 years
Number of equity shares			55,300	55,300
Contribution of pension fund			$ 0	$ 3,000,000	$ 2,500,000
Eligible employee contributions specified percentage one			3.00%	3.00%	3.00%
Eligible employee contributions specified percentage two			2.00%	2.00%	2.00%
ESOP			$ 0	$ 0	$ 0
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			142,600
Stock options granted to selected participants exercise price per share			$ 21.55
Total intrinsic value of options exercised			$ 45,000	$ 132,000
Cash received from stock option exercised			153,000	157,000
Tax benefit realized from stock options exercised			11,000	30,000
Total intrinsic value of the outstanding shares			2,200,000
Total intrinsic value of the shares exercisable			1,600,000
Total Assets			16,425,610,000	15,720,112,000
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			$ 400,000	400,000	$ 500,000
Expense recognition period			2 years 4 months 24 days
Number of shares granted					12,000
Number of share vested that granted 2017			0
Grant date fair value			$ 24.46
Total unrecognized compensation expense			$ 400,000
key Officers [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense for Annual Bonus			$ 1,700,000	2,100,000	$ 2,000,000.0
KSOP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares held by KSOP			483,734
Total expense for the KSOP/Compensation expense for the stock option component of the Plan			$ 5,300,000	$ 4,400,000	3,700,000
Future issuance under equity compensation plans			246,769	343,107
Equity Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Future issuance under equity compensation plans			35,711	408,466
Additional common stock for issuance			1,000,000
Selected Participants Including Certain Executive Officers [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted to selected participants	142,600
Stock options granted to selected participants exercise price per share	$ 21.55
Stock Option [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			$ 600,000	$ 900,000	600,000
Options grant expired			7 years
Total unrecognized compensation expense related to non-vested stock option grants			$ 200,000
Expense recognition period			1 year
Stock Option [Member] | 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			176,924
Fair value of restricted stock granted			$ 21.58
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			30,298
Restricted shares vesting period			3 years
Performance Based Restricted Stock [Member] | Vesting on May 16, 2021 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 16, 2022 [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]
Total Assets			$ 37,700,000,000
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]
Total Assets			$ 10,800,000,000
2017 Performance Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted			2,550
Performance targets achieved, percentage			85.00%
2018 Performance Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted			2,289
Performance targets achieved, percentage			85.00%
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			$ 4,600,000	$ 4,200,000	$ 3,000,000.0
Expense recognition period			1 year 6 months
Number of shares granted			207,222
Fair value of restricted stock granted			$ 21.58
Total unrecognized compensation expense related to non-vested restricted stock grants			$ 7,000,000.0
Number of share vested that granted 2017			89,954
Grant date fair value			$ 32.90	$ 40.75
Shareholder Return Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
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
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
Total Assets						$ 1,600,000,000
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	$ 2,100,000