Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Class A	Class B	Total Stockholders' Equity Before Noncontrolling Interest	Total Stockholders' Equity Before Noncontrolling Interest Class A	Total Stockholders' Equity Before Noncontrolling Interest Class B	Common Stock Class A	Common Stock Class B	Additional Paid in Capital	Treasury Stock	Treasury Stock Class A	Treasury Stock Class B	Retained Earnings	Accumulated Other Comprehensive Income (loss)	Noncontrolling interest
Beginning balance (in shares) at Dec. 31, 2020							28,806,344	9,036,352
Beginning balance at Dec. 31, 2020	$ 783,421			$ 783,421			$ 2,882	$ 904	$ 305,569	$ 0			$ 442,402	$ 31,664	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock (in shares)								(116,037)
Repurchase of common stock			$ (1,855)			$ (1,855)						$ (1,855)
Treasury stock retired	0			0				$ (12)	(1,843)	1,855
Restricted stock issued (in shares)							196,015
Restricted stock issued	0			0			$ 22		(22)
Restricted stock surrendered (in shares)							(713)
Restricted stock surrendered	(13)			(13)					(13)
Stock-based compensation expense	757			757					757
Net income attributable to Amerant Bancorp Inc.	14,459			14,459									14,459
Other comprehensive (loss) income	(11,755)			(11,755)										(11,755)
Ending balance (in shares) at Mar. 31, 2021							29,001,646	8,920,315
Ending balance at Mar. 31, 2021	785,014			785,014			$ 2,904	$ 892	304,448	0			456,861	19,909	0
Beginning balance (in shares) at Dec. 31, 2020							28,806,344	9,036,352
Beginning balance at Dec. 31, 2020	783,421			783,421			$ 2,882	$ 904	305,569	0			442,402	31,664	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to Amerant Bancorp Inc.	30,421
Net loss attributable to noncontrolling-interest shareholders	(817)
Other comprehensive (loss) income	(7,906)
Ending balance (in shares) at Jun. 30, 2021							29,028,672	8,534,120
Ending balance at Jun. 30, 2021	799,068			799,885			$ 2,904	$ 853	299,547	0			472,823	23,758	(817)
Beginning balance (in shares) at Mar. 31, 2021							29,001,646	8,920,315
Beginning balance at Mar. 31, 2021	785,014			785,014			$ 2,904	$ 892	304,448	0			456,861	19,909	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock (in shares)								(386,195)
Repurchase of common stock			$ (6,540)			$ (6,540)						$ (6,540)
Treasury stock retired	0			0				$ (39)	(6,501)	6,540
Performance share units vested (in shares)							1,729
Performance share units vested	0			0
Restricted stock surrendered (in shares)							(1,213)
Restricted stock surrendered	(26)			(26)					(26)
Restricted stock forfeited (in shares)							(7,270)
Restricted stock forfeited	0			0			$ (2)		2
Restricted stock units vested (in shares)							33,780
Restricted stock units vested	0			0			$ 2		(2)
Stock-based compensation expense	1,626			1,626					1,626
Net income attributable to Amerant Bancorp Inc.	15,962			15,962									15,962
Net loss attributable to noncontrolling-interest shareholders	(817)			0											(817)
Other comprehensive (loss) income	3,849			3,849										3,849
Ending balance (in shares) at Jun. 30, 2021							29,028,672	8,534,120
Ending balance at Jun. 30, 2021	$ 799,068			799,885			$ 2,904	$ 853	299,547	0			472,823	23,758	(817)
Beginning balance (in shares) at Dec. 31, 2021	35,883,320						35,883,320
Beginning balance at Dec. 31, 2021	$ 831,873			834,483			$ 3,589		262,510	0			553,167	15,217	(2,610)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock (in shares)							(1,643,480)
Repurchase of 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.	15,950			15,950									15,950
Dividends paid	(3,154)			(3,154)									(3,154)
Net loss attributable to noncontrolling-interest shareholders	(1,076)			0											(1,076)
Other comprehensive (loss) income	(39,641)			(39,641)										(39,641)
Ending balance (in shares) at Mar. 31, 2022							34,350,822
Ending balance at Mar. 31, 2022	$ 749,396			753,082			$ 3,434		208,109	0			565,963	(24,424)	(3,686)
Beginning balance (in shares) at Dec. 31, 2021	35,883,320						35,883,320
Beginning balance at Dec. 31, 2021	$ 831,873			834,483			$ 3,589		262,510	0			553,167	15,217	(2,610)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to Amerant Bancorp Inc.	23,624
Net loss attributable to noncontrolling-interest shareholders	(1,148)
Other comprehensive (loss) income	$ (66,176)
Ending balance (in shares) at Jun. 30, 2022	33,759,604						33,759,604
Ending balance at Jun. 30, 2022	$ 711,450			713,341			$ 3,375		190,337	0			570,588	(50,959)	(1,891)
Beginning balance (in shares) at Mar. 31, 2022							34,350,822
Beginning balance at Mar. 31, 2022	749,396			753,082			$ 3,434		208,109	0			565,963	(24,424)	(3,686)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock (in shares)							(611,525)
Repurchase of common stock		$ (17,240)			$ (17,240)						$ (17,240)
Treasury stock retired	0			0			$ (61)		(17,179)	17,240
Restricted stock issued (in shares)							37,938
Restricted stock issued	0			0			$ 4		(4)
Restricted stock forfeited (in shares)							(28,586)
Restricted stock forfeited	0			0			$ (3)		3
Restricted stock units vested (in shares)							10,955
Restricted stock units vested	0			0			$ 1		(1)
Stock-based compensation expense	1,276			1,276					1,276
Net income attributable to Amerant Bancorp Inc.	7,674			7,674									7,674
Dividends paid	(3,049)			(3,049)									(3,049)
Transfer of subsidiary shares from noncontrolling interest	0			(1,867)					(1,867)						1,867
Net loss attributable to noncontrolling-interest shareholders	(72)			0											(72)
Other comprehensive (loss) income	$ (26,535)			(26,535)										(26,535)
Ending balance (in shares) at Jun. 30, 2022	33,759,604						33,759,604
Ending balance at Jun. 30, 2022	$ 711,450			$ 713,341			$ 3,375		$ 190,337	$ 0			$ 570,588	$ (50,959)	$ (1,891)