Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022
Earnings Per Share [Abstract]
Net income before attribution of noncontrolling interest	$ 7,046		$ 8,352		$ 26,988	$ 22,655
Noncontrolling interest	(262)	$ (244)	(72)	$ (1,076)	(506)	(1,148)
Net income attributable to Amerant Bancorp Inc.	$ 7,308	$ 20,186	$ 8,424	$ 15,379	$ 27,494	$ 23,803
Basic weighted average shares outstanding (in shares)	33,564,770		33,675,930		33,562,258	34,244,797
Dilutive effect of share-based compensation awards (in shares)	152,932		238,599		224,604	266,329
Diluted weighted average shares outstanding (in shares)	33,717,702		33,914,529		33,786,862	34,511,126
Basic earnings per common share (in dollars per share)	$ 0.22		$ 0.25		$ 0.82	$ 0.70
Diluted earnings per common share (in dollars per share)	$ 0.22		$ 0.25		$ 0.81	$ 0.69
Non-vested shares (in shares)	542,745		521,162		542,745	521,162