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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=118936363&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

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

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

+ Details

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

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

+ Details

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

- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=118939070&loc=d3e15032-111544

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 6.L.1)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707

+ Details

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

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5074-111524

+ Details

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

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=bpfh_CommercialandIndustrialPortfolioSegmentMember
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_ConstructionLoansMember
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_HomeEquityMember
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:

Allowance for Loan Losses Allowance by impairment analysis method (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Impairment Recorded investment (loan balance)	$ 20,786		$ 15,643
Individually Evaluated for Impairment Allowance for loan losses	191		1,235
Collectively Evaluated for Impairment Recorded investment (loan balance)	7,059,474		6,877,515
Collectively Evaluated for Impairment Allowance for loan losses	74,876		74,077
Total Loans Receivable	7,080,260		6,893,158
Allowance for loan losses	75,067	$ 73,814	75,312	$ 73,464	$ 72,898	$ 74,742
Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Impairment Recorded investment (loan balance)	2,110		3,205
Individually Evaluated for Impairment Allowance for loan losses	93		598
Collectively Evaluated for Impairment Recorded investment (loan balance)	1,104,383		1,071,503
Collectively Evaluated for Impairment Allowance for loan losses	15,989		15,314
Total Loans Receivable	1,106,493		1,074,708
Allowance for loan losses	16,082	15,687	15,912	12,381	11,443	11,735
Commercial real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Impairment Recorded investment (loan balance)	0		546
Individually Evaluated for Impairment Allowance for loan losses	0		0
Collectively Evaluated for Impairment Recorded investment (loan balance)	2,530,556		2,395,146
Collectively Evaluated for Impairment Allowance for loan losses	43,741		41,934
Total Loans Receivable	2,530,556		2,395,692
Allowance for loan losses	43,741	41,813	41,934	45,183	46,116	46,820
Construction and land
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Impairment Recorded investment (loan balance)	0		0
Individually Evaluated for Impairment Allowance for loan losses	0		0
Collectively Evaluated for Impairment Recorded investment (loan balance)	200,378		240,306
Collectively Evaluated for Impairment Allowance for loan losses	4,780		6,022
Total Loans Receivable	200,378		240,306
Allowance for loan losses	4,780	5,353	6,022	4,613	4,533	4,949
Residential
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Impairment Recorded investment (loan balance)	15,905		9,183
Individually Evaluated for Impairment Allowance for loan losses	74		75
Collectively Evaluated for Impairment Recorded investment (loan balance)	3,009,853		2,939,790
Collectively Evaluated for Impairment Allowance for loan losses	9,481		9,951
Total Loans Receivable	3,025,758		2,948,973
Allowance for loan losses	9,555	10,057	10,026	9,804	9,896	9,773
Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Impairment Recorded investment (loan balance)	2,771		2,709
Individually Evaluated for Impairment Allowance for loan losses	24		562
Collectively Evaluated for Impairment Recorded investment (loan balance)	87,159		87,712
Collectively Evaluated for Impairment Allowance for loan losses	781		722
Total Loans Receivable	89,930		90,421
Allowance for loan losses	805	796	1,284	1,336	784	835
Consumer and other
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Impairment Recorded investment (loan balance)	0		0
Individually Evaluated for Impairment Allowance for loan losses	0		0
Collectively Evaluated for Impairment Recorded investment (loan balance)	127,145		143,058
Collectively Evaluated for Impairment Allowance for loan losses	104		134
Total Loans Receivable	127,145		143,058
Allowance for loan losses	$ 104	$ 108	$ 134	$ 147	$ 126	$ 630