REGULATORY MATTERS - Dividend Restrictions (Details)	9 Months Ended
Sep. 30, 2018
REGULATORY MATTERS
Dividend restrictions term	2 years

Number of preceding years for which approval is also required if dividends declared exceed the net profits for that year combined with the retained net profits.

No definition available.

Name:	cbtx_DividendRestrictionsTerm
Namespace Prefix:	cbtx_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration