Loans and reserve for credit losses (Receivable) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2016	Sep. 30, 2016
Covered Loans, Loss Share Payable (Receivable) [Roll Forward]
Balance at beginning of period	$ 201	$ 289
Paid to FDIC	(201)	(857)
Increase due to impairment	0	(53)
FDIC reimbursement	396	1,077
Shared loss expenses	(28)	(92)
Adjustments from prior periods	0	4
Balance at end of period	$ 368	$ 368

Covered Loans, Loss Share Payable (Receivable), FDIC Reimbursement

No definition available.

Name:	cacb_CoveredLoansLossSharePayableReceivableFDICReimbursement
Namespace Prefix:	cacb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Covered Loans, Loss Shared Payable (Receivable), Net

No definition available.

Name:	cacb_CoveredLoansLossSharePayableReceivableNet
Namespace Prefix:	cacb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Covered Loans, Loss Share Payable (Receivable), Shared Income

No definition available.

Name:	cacb_CoveredLoansLossSharePayableReceivableSharedIncome
Namespace Prefix:	cacb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Covered Loans, Loss Share Payable (Receivable), Shared Loss Expense

No definition available.

Name:	cacb_CoveredLoansLossSharePayableReceivableSharedLossExpense
Namespace Prefix:	cacb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Covered Loans, Loss Share Payable (Receivable), Amount Paid From (Paid To) FDIC

No definition available.

Name:	cacb_CoveredLoansLossSharedPayableReceivableAmountPaidFromPaidToFDIC
Namespace Prefix:	cacb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Covered Loans, Loss Share Payable (Receivable,) Decrease (Increase) Due To Impairment

No definition available.

Name:	cacb_CoveredLoansLossSharedPayableReceivableDecreaseIncreaseDueToImpairment
Namespace Prefix:	cacb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Loans and Leases Receivable, Covered [Roll Forward]

No definition available.

Name:	cacb_LoansandLeasesReceivableCoveredRollForward
Namespace Prefix:	cacb_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration