Allowance for Loan Losses - Balance in Allowance for Loan Losses and Recorded Investment in Loans by Impairment (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Financing Receivable Impaired [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment		$ 30
Allowance for Loan Losses, Collectively Evaluated for Impairment	$ 13,600	10,570
Total Allowance for Loan Losses	13,600	10,600
Unaccreted Credit Component Other Loans	481	732
Loans, Individually Evaluated for Impairment	7,698	12,038
Loans, Collectively Evaluated for Impairment	2,293,803	1,746,772
Total loans	2,306,371	1,765,469
Unaccreted Credit Component Other Loans	64,524	85,293
Receivables Acquired with Deteriorated Credit Quality
Financing Receivable Impaired [Line Items]
Loans, Purchased Impaired	4,870	6,659
Residential Properties
Financing Receivable Impaired [Line Items]
Allowance for Loan Losses, Collectively Evaluated for Impairment	6,304	6,799
Total Allowance for Loan Losses	6,304	6,799
Unaccreted Credit Component Other Loans	148	127
Loans, Individually Evaluated for Impairment	3,844
Loans, Collectively Evaluated for Impairment	1,559,963	1,160,568
Total loans	1,563,807	1,160,568
Unaccreted Credit Component Other Loans	13,472	7,747
Commercial Real Estate
Financing Receivable Impaired [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment		30
Allowance for Loan Losses, Collectively Evaluated for Impairment	2,628	1,783
Total Allowance for Loan Losses	2,628	1,813
Unaccreted Credit Component Other Loans	149	363
Loans, Individually Evaluated for Impairment	1,187	6,275
Loans, Collectively Evaluated for Impairment	458,334	352,162
Total loans	459,703	358,791
Unaccreted Credit Component Other Loans	24,982	43,287
Commercial Real Estate \| Receivables Acquired with Deteriorated Credit Quality
Financing Receivable Impaired [Line Items]
Loans, Purchased Impaired	182	354
Commercial and Industrial Loans
Financing Receivable Impaired [Line Items]
Allowance for Loan Losses, Collectively Evaluated for Impairment	4,170	1,649
Total Allowance for Loan Losses	4,170	1,649
Unaccreted Credit Component Other Loans	161	187
Loans, Individually Evaluated for Impairment	2,653	5,687
Loans, Collectively Evaluated for Impairment	221,238	185,732
Total loans	228,579	196,584
Unaccreted Credit Component Other Loans	24,157	28,231
Commercial and Industrial Loans \| Receivables Acquired with Deteriorated Credit Quality
Financing Receivable Impaired [Line Items]
Loans, Purchased Impaired	4,688	5,165
Consumer Loans
Financing Receivable Impaired [Line Items]
Allowance for Loan Losses, Collectively Evaluated for Impairment	296	236
Total Allowance for Loan Losses	296	236
Unaccreted Credit Component Other Loans	20	13
Loans, Individually Evaluated for Impairment	14	76
Loans, Collectively Evaluated for Impairment	34,234	37,130
Total loans	34,248	37,206
Unaccreted Credit Component Other Loans	1,477	1,761
Land and Construction
Financing Receivable Impaired [Line Items]
Allowance for Loan Losses, Collectively Evaluated for Impairment	202	103
Total Allowance for Loan Losses	202	103
Unaccreted Credit Component Other Loans	3	42
Loans, Collectively Evaluated for Impairment	20,034	11,180
Total loans	20,034	12,320
Unaccreted Credit Component Other Loans	$ 436	4,267
Land and Construction \| Receivables Acquired with Deteriorated Credit Quality
Financing Receivable Impaired [Line Items]
Loans, Purchased Impaired		$ 1,140

Allowance for loan losses in unaccreted credit component other loans.

No definition available.

Name:	ffwm_AllowanceForLoanLossesInUnaccretedCreditComponentOtherLoans
Namespace Prefix:	ffwm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Loans and lease receivable in unaccreted credit component other loan.

+ References

No definition available.

+ Details

Name:	ffwm_LoansAndLeaseReceivableInUnaccretedCreditComponentOtherLoan
Namespace Prefix:	ffwm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Loans And Leases Receivable Allowance Impaired.

+ References

No definition available.

+ Details

Name:	ffwm_LoansAndLeasesReceivableAllowanceImpaired
Namespace Prefix:	ffwm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The balance of financing receivables that were collectively evaluated for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FinancingReceivableImpairedLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The balance of financing receivables that were individually evaluated for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=65884687&loc=d3e4428-111522

+ Details

Name:	us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_NotesReceivableNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis=us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: