Significant Accounting Policies - Additional Information (Detail) - Maximum [Member]	9 Months Ended
Sep. 30, 2017
Significant Accounting Policies [Line Items]
Percentage of increase on assets due to new accounting standard updates	1.00%
Percentage of increase on liabilities due to new accounting standard updates	1.00%

Percentage of impact on liabilities due to new accounting standard updates.

No definition available.

Name:	civb_PercentageOfImpactOnLiabilitiesDueToNewAccountingStandardUpdates
Namespace Prefix:	civb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration