v3.8.0.1

Allowance for Loan Losses - Additional Information (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016
Receivables [Abstract] |  |
Allowance of purchase impaired loans | 1.15% | 0.73%
Additional allowance on credit impaired loans | $ 200,000 | $ 500,000
Interest income recognized on impaired loans | $ 0 | $ 0

X
- Definition Additional allowance on credit impaired loans. + References No definition available. + Details
Name: | ffwm_AdditionalAllowanceOnCreditImpairedLoans
Namespace Prefix: | ffwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Percentage of allowance on purchase impaired loans. + References No definition available. + Details
Name: | ffwm_PercentageOfAllowanceOnPurchaseImpairedLoans
Namespace Prefix: | ffwm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of interest income recognized on a cash-basis method of accounting that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableInterestIncomeCashBasisMethod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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