Business Acquisitions - Narrative (Details) $ / shares in Units, $ in Thousands			3 Months Ended		9 Months Ended
	Aug. 01, 2021 USD ($) shares	May 01, 2019 USD ($) bank $ / shares shares	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Business Acquisition [Line Items]
Goodwill			$ 52,706		$ 52,706		$ 15,992
Goodwill adjustment					0	$ 485
SouthCrest Financial Group, Inc.
Business Acquisition [Line Items]
Number of banking locations | bank		8
Cash paid in exchange for each share (in dollars per share) | $ / shares		$ 10.45
Shares exchanged for each share (in shares) | shares		0.7318
Shares of CBAN common stock issued to Southcrest shareholders (in shares) | shares		3,987,898
Estimated fair value of CBAN common stock issued		$ 71,400
Cash consideration paid		$ 21,600
Goodwill	$ 35,037
Revenue of acquiree since acquisition date, actual			3,000		3,000
Net income of acquiree since acquisition date, actual			2,300		2,300
Pro forma revenue			28,900	$ 29,500	90,900	82,600
Pro forma net income (loss)			4,300	$ 5,500	$ 16,600	$ 5,800
Credit impaired loans acquired	$ 306,302
LBC Bancshares, Inc
Business Acquisition [Line Items]
Shares of CBAN common stock issued to Southcrest shareholders (in shares) | shares	3,987,815
Estimated fair value of CBAN common stock issued	$ 71,382
Cash consideration paid	21,620
Loans	307,456
Discount on loans purchased	$ 635
Discount on loans purchased, percentage of loan value	2.07%
Credit impaired loans acquired	$ 1,154
Insurance Agencies
Business Acquisition [Line Items]
Goodwill adjustment			1,700
Insurance Agencies | Customer Deposits
Business Acquisition [Line Items]
Finite-lived intangible assets acquired			$ 1,700