Regulatory Matters - Summary of Capital Ratios (Detail) $ in Thousands	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Risk Based Ratios [Abstract]
Total capital (to risk-weighted assets), For capital adequacy purposes , ratio		10.50
Company
Total capital (to risk-weighted assets)
Total capital (to risk-weighted assets)	$ 783,107	$ 721,741
Total capital (to risk-weighted assets), For capital adequacy purposes	640,632	565,504
Tier 1 capital (to risk-weighted assets)
Tier 1 capital (to risk-weighted assets)	623,644	593,539
Tier 1 capital (to risk-weighted assets), For capital adequacy purposes	518,607	457,789
Common equity Tier 1 capital (to risk-weighted assets)
Common equity Tier 1 capital (to risk-weighted assets)	593,644	563,539
Common equity Tier 1 capital (to risk-weighted assets), For capital adequacy purposes	427,088	377,003
Tier 1 capital (to average assets)
Tier 1 capital (to average assets)	623,644	593,539
Tier 1 capital (to average assets), For capital adequacy purposes	$ 298,096	$ 252,234
Risk Based Ratios [Abstract]
Total capital (to risk-weighted assets), ratio	0.1284	0.1340
Tier 1 capital (to risk-weighted assets), ratio	0.1022	0.1102
Common equity Tier 1 capital (to risk-weighted assets), ratio	0.0973	0.1046
Tier 1 capital (to average assets), ratio	0.0837	0.0941
Total capital (to risk-weighted assets), For capital adequacy purposes , ratio	10.50
Tier 1 capital (to risk-weighted assets), For capital adequacy purposes, ratio	8.50	8.50
Common equity Tier 1 capital (to risk-weighted assets), For capital adequacy purposes, ratio	700.00%	700.00%
Tier 1 capital (to average assets), For capital adequacy purposes, ratio	4.00	4.00
Total capital (to risk - weighted assets), To be well capitalized under prompt corrective action provisions, ratio	10.00	10.00
Tier 1 capital (to risk-weighted assets), To be well capitalized under prompt corrective action provisions, ratio	8.00	8.00
Common equity Tier 1 capital (to risk-weighted assets), To be well capitalized under prompt corrective action provisions, ratio	650.00%	650.00%
Tier 1 capital (to average assets), To be well capitalized under prompt corrective action provisions, ratio	5.00	5.00
Lakeland
Total capital (to risk-weighted assets)
Total capital (to risk-weighted assets)	$ 745,276	$ 681,689
Total capital (to risk-weighted assets), For capital adequacy purposes	640,416	564,981
Total capital (to risk - weighted assets), To be well capitalized under prompt corrective action provisions	609,920	538,077
Tier 1 capital (to risk-weighted assets)
Tier 1 capital (to risk-weighted assets)	672,832	639,908
Tier 1 capital (to risk-weighted assets), For capital adequacy purposes	518,432	457,365
Tier 1 capital (to risk-weighted assets), To be well capitalized under prompt corrective action provisions	487,936	430,462
Common equity Tier 1 capital (to risk-weighted assets)
Common equity Tier 1 capital (to risk-weighted assets)	672,832	639,908
Common equity Tier 1 capital (to risk-weighted assets), For capital adequacy purposes	426,944	376,654
Common equity Tier 1 capital (to risk-weighted assets), To be well capitalized under prompt corrective action provisions	396,448	349,750
Tier 1 capital (to average assets)
Tier 1 capital (to average assets)	672,832	639,908
Tier 1 capital (to average assets), For capital adequacy purposes	297,748	252,039
Tier 1 capital (to average assets), To be well capitalized under prompt corrective action provisions	$ 372,185	$ 315,048
Risk Based Ratios [Abstract]
Total capital (to risk-weighted assets), ratio	0.1222	0.1267
Tier 1 capital (to risk-weighted assets), ratio	0.1103	0.1189
Common equity Tier 1 capital (to risk-weighted assets), ratio	0.1103	0.1189
Tier 1 capital (to average assets), ratio	0.0904	0.1016
Total capital (to risk-weighted assets), For capital adequacy purposes , ratio	0.1050	0.1050
Tier 1 capital (to risk-weighted assets), For capital adequacy purposes, ratio	0.0850	0.0850
Common equity Tier 1 capital (to risk-weighted assets), For capital adequacy purposes, ratio	7.00%	7.00%
Tier 1 capital (to average assets), For capital adequacy purposes, ratio	0.0400	0.0400

Common Equity Tier One Leverage Capital Required for Capital Adequacy

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