Mergers and Acquisitions - Pro Forma Combined Condensed Consolidated Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017
Brand Mortgage Group, LLC
Business Acquisition [Line Items]
Interest income	$ 186	$ 186
Interest expense	143	143
Net interest income	43	43
Noninterest income	1,696	1,696
Noninterest expense	2,029	2,029
Net income before taxes	$ (290)	(290)
Metropolitan Bancgroup, Inc.
Business Acquisition [Line Items]
Net interest income		341,946	$ 336,250
Noninterest income		117,476	139,328
Noninterest expense		359,386	327,566
Net income before taxes		$ 72,719	$ 93,570
Earnings per share - pro forma:
Basic (usd per share)		$ 1.24	$ 1.60
Diluted (usd per share)		$ 1.24	$ 1.59