Condensed Unconsolidated Holding Companies’ Financial Statements - Balance Sheet Information (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assets
Cash and due from banks	$ 33,668	$ 30,179
Investments in subsidiaries	62,250	62,250
U.S. treasury securities	1,341,241	1,372,567
Total assets	7,638,399	7,770,893
Liabilities and Stockholders' Equity
Junior subordinated debentures held by trust subsidiaries	64,178	64,178
Senior notes	58,894	58,577
Total stockholders' equity	831,873	783,421	$ 834,701	$ 747,418
Total liabilities and stockholders' equity	7,638,399	7,770,893
Mercantil Bank Holding Corporation | Parent Company | Reportable Legal Entities
Assets
Cash and due from banks	23,810	43,029
Investments in subsidiaries	870,560	798,339
Other assets	1,872	1,617
Total assets	896,242	842,985
Liabilities and Stockholders' Equity
Other liabilities	2,865	987
Total stockholders' equity	834,483	783,421
Total liabilities and stockholders' equity	896,242	842,985
Mercantil Florida Bancorp, Inc | Subsidiaries | Reportable Legal Entities
Assets
Cash and due from banks	6,340	16,559
Investments in subsidiaries	918,212	840,866
U.S. treasury securities	2,502	2,512
Other assets	3,622	5,592
Total assets	930,676	865,529
Liabilities and Stockholders' Equity
Junior subordinated debentures held by trust subsidiaries	64,178	64,178
Other liabilities	2,038	3,012
Total stockholders' equity	864,460	798,339
Total liabilities and stockholders' equity	$ 930,676	$ 865,529