Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Cumulative effect of adoption of accounting principle, net of tax	Class A	Total Stockholders' Equity Before Noncontrolling Interest	Total Stockholders' Equity Before Noncontrolling Interest Cumulative effect of adoption of accounting principle, net of tax	Total Stockholders' Equity Before Noncontrolling Interest Class A	Common Stock Class A	Additional Paid in Capital	Treasury Stock	Treasury Stock Class A	Retained Earnings	Retained Earnings Cumulative effect of adoption of accounting principle, net of tax	Accumulated Other Comprehensive Income (loss)	Noncontrolling interest
Beginning balance (in shares) at Dec. 31, 2021							35,883,320
Beginning balance at Dec. 31, 2021	$ 831,873	$ (13,872)		$ 834,483	$ (13,872)		$ 3,589	$ 262,510	$ 0		$ 553,167	$ (13,872)	$ 15,217	$ (2,610)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of Class A common stock (in shares)							(1,643,480)
Repurchase of Class A common stock			$ (54,820)			$ (54,820)				$ (54,820)
Treasury stock retired	0			0			$ (165)	(54,655)	54,820
Restricted stock issued (in shares)							104,762
Restricted stock issued	0			0			$ 10	(10)
Restricted stock surrendered (in shares)							(15,174)
Restricted stock surrendered	(996)			(996)			$ (2)	(994)
Restricted stock forfeited (in shares)							(1,000)
Restricted stock forfeited	0			0
Restricted stock units vested (in shares)							22,394
Restricted stock units vested	0			0			$ 2	(2)
Stock-based compensation expense	1,260			1,260				1,260
Net income attributable to Amerant Bancorp Inc.	15,379			15,379							15,379
Dividends paid	(3,154)			(3,154)							(3,154)
Net loss attributable to noncontrolling-interest shareholders	(1,076)			0										(1,076)
Other comprehensive income (loss)	(39,641)			(39,641)									(39,641)
Ending balance (in shares) at Mar. 31, 2022							34,350,822
Ending balance at Mar. 31, 2022	$ 734,953			738,639			$ 3,434	208,109	0		551,520		(24,424)	(3,686)
Beginning balance (in shares) at Dec. 31, 2022	33,815,161						33,815,161
Beginning balance at Dec. 31, 2022	$ 705,726			707,816			$ 3,382	194,694	0		590,375		(80,635)	(2,090)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of Class A common stock (in shares)							(22,403)
Repurchase of Class A common stock			$ (566)			$ (566)				$ (566)
Treasury stock retired	0			0			$ (2)	(564)	566
Restricted stock issued (in shares)							10,440
Restricted stock issued	0			0			$ 1	(1)
Restricted stock, restricted stock units and performance stock units surrendered (in shares)							(44,896)
Restricted stock, restricted stock units and performance stock units surrendered	(1,170)			(1,170)			$ (4)	(1,166)
Restricted stock forfeited (in shares)							(1,394)
Restricted stock forfeited	0			0
Performance stock units vested (in shares)							10,621
Performance stock units vested	0			0			$ 1	(1)
Restricted stock units vested (in shares)							46,731
Restricted stock units vested	0			0			$ 5	(5)
Stock-based compensation expense	1,825			1,825				1,825
Net income attributable to Amerant Bancorp Inc.	20,186			20,186							20,186
Dividends paid	(3,017)			(3,017)							(3,017)
Net loss attributable to noncontrolling-interest shareholders	(244)			0										(244)
Other comprehensive income (loss)	$ 6,316			6,316									6,316
Ending balance (in shares) at Mar. 31, 2023	33,814,260						33,814,260
Ending balance at Mar. 31, 2023	$ 729,056			$ 731,390			$ 3,383	$ 194,782	$ 0		$ 607,544		$ (74,319)	$ (2,334)