v3.8.0.1

Commitment and Contingencies - Off Balance Sheet Arrangements of Bank (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016
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Commitments And Contingencies Disclosure [Abstract] |  |
Commitments to fund new loans | $ 44,561 | $ 43,006
Commitments to fund under existing loans, lines of credit | 211,712 | 211,745
Commitments under standby letters of credit | $ 2,352 | $ 4,830

X
- Definition Commitments to fund new loans. + References No definition available. + Details
Name: | ffwm_CommitmentsToFundNewLoans
Namespace Prefix: | ffwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Commitments to fund under existing loans lines of credit. + References No definition available. + Details
Name: | ffwm_CommitmentsToFundUnderExistingLoansLinesOfCredit
Namespace Prefix: | ffwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Commitments under standby letters of credit. + References No definition available. + Details
Name: | ffwm_CommitmentsUnderStandbyLettersOfCredit
Namespace Prefix: | ffwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_CommitmentsAndContingenciesDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration