Note 8 - Commitments - Summary of Overdraft Protection (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Overdraft protection available on depositors' accounts	$ 8,125	$ 8,070
Balance of overdrafts included in loans	83	130
Average daily balance of overdrafts	$ 463	$ 112
Average daily balance of overdrafts as a percentage of available	5.70%	1.39%

The average daily overdrafts on accounts expressed as a percentage of total available.

No definition available.

Name:	cldb_AverageDailyOverdraftsPercentageOfAvailable
Namespace Prefix:	cldb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant