XML 77 R66.htm IDEA: XBRL DOCUMENT
v3.20.2

FDIC Shared-Loss Payable FDIC Shared-Loss Payable (Changes in Payable to FDIC) (Details) $ in Thousands | 9 Months Ended
--- | ---
Sep. 30, 2020 USD ($)
FDIC Shared-Payable [Abstract] |
FDIC shared-loss payable | $ 112,395
Accretion | 2,386
Payment made to the FDIC to settle shared-loss agreement | (99,468)
FDIC shared-loss payable | $ 15,313

X
- Definition Amount of accretion expense for FDIC shared-loss payable. + References No definition available. + Details
Name: | fcnca_AccretionOfFDICSharedLossPayable
Namespace Prefix: | fcnca_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition FDIC shared-loss payable adjustments related to changes in assumptions. + References No definition available. + Details
Name: | fcnca_FDICSharedLossPayableAdjustments
Namespace Prefix: | fcnca_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition FDIC Shared-Payable [Abstract] + References No definition available. + Details
Name: | fcnca_FDICSharedPayableAbstract
Namespace Prefix: | fcnca_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Payable to FDIC for Loss Share Agreements + References No definition available. + Details
Name: | fcnca_PayableToFdicForLossShareAgreements
Namespace Prefix: | fcnca_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant