Note 15 - Shareholders' Equity and Regulatory Matters - (Tables)

12 Months Ended

Dec. 31, 2022

Notes Tables

Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block]

											To Be Well
											Capitalized Under
						For Capital					Prompt Corrective
Business First Bancshares, Inc. (Consolidated)	Actual					Adequacy Purposes					Action Provisions
	Amount		Ratio			Amount		Ratio			Amount		Ratio
December 31, 2022:	(Dollars in thousands)
Total Capital (to Risk-Weighted Assets)	$	704,840		12.75	%	$	442,391		8.00	%	$	552,988		10.00	%
Tier 1 Capital (to Risk-Weighted Assets)		557,088		10.07	%		331,793		6.00	%		442,391		8.00	%
Common Equity Tier 1 Capital (to Risk-Weighted Assets)		480,158		8.68	%		248,845		4.50	%		359,442		N/A
Tier 1 Leveraged Capital (to Average Assets)		557,088		9.49	%		234,859		4.00	%		293,574		N/A
December 31, 2021:
Total Capital (to Risk-Weighted Assets)	$	478,794		11.94	%	$	320,715		8.00	%	$	400,894		10.00	%
Tier 1 Capital (to Risk-Weighted Assets)		367,431		9.17	%		240,537		6.00	%		320,715		8.00	%
Common Equity Tier 1 Capital (to Risk-Weighted Assets)		362,431		9.04	%		180,402		4.50	%		260,581		N/A
Tier 1 Leveraged Capital (to Average Assets)		367,431		8.14	%		180,604		4.00	%		225,755		N/A

											To Be Well
											Capitalized Under
						For Capital					Prompt Corrective
b1BANK	Actual					Adequacy Purposes					Action Provisions
	Amount		Ratio			Amount		Ratio			Amount		Ratio
December 31, 2022:	(Dollars in thousands)
Total Capital (to Risk-Weighted Assets)	$	657,588		11.91	%	$	441,833		8.00	%	$	552,292		10.00	%
Tier 1 Capital (to Risk-Weighted Assets)		618,805		11.20	%		331,375		6.00	%		441,833		8.00	%
Common Equity Tier 1 Capital (to Risk-Weighted Assets)		618,805		11.20	%		248,531		4.50	%		358,989		6.50	%
Tier 1 Leveraged Capital (to Average Assets)		618,805		10.55	%		234,679		4.00	%		293,348		5.00	%
December 31, 2021:
Total Capital (to Risk-Weighted Assets)	$	468,834		11.71	%	$	320,411		8.00	%	$	400,514		10.00	%
Tier 1 Capital (to Risk-Weighted Assets)		438,898		10.96	%		240,308		6.00	%		320,411		8.00	%
Common Equity Tier 1 Capital (to Risk-Weighted Assets)		438,898		10.96	%		180,231		4.50	%		260,334		6.50	%
Tier 1 Leveraged Capital (to Average Assets)		438,898		9.73	%		180,453		4.00	%		225,566		5.00	%