The amount of junior subordinated debentures assumed which have been recognized as of the acquisition date.

No definition available.

Name:	bmtc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedJuniorSubordinatedDebentures
Namespace Prefix:	bmtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of capital securities initially bearing fixed and/or fixed/floating interest rates corresponding to the debt securities held by a trust to an unaffiliated investment vehicle.

+ References

No definition available.

+ Details

Name:	bmtc_TrustCapitalSecuritiesIssued
Namespace Prefix:	bmtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of common securities bearing fixed and or fixed/floating interest rates corresponding to the debt securities held by a trust.

+ References

No definition available.

+ Details

Name:	bmtc_TrustCommonSecuritiesIssued
Namespace Prefix:	bmtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6036836-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of investments classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(f,g))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Details

Name:	dei_LegalEntityAxis=bmtc_RoyalBancsharesCapitalTrustIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=bmtc_RoyalBancsharesCapitalTrustIIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=bmtc_JuniorSubordinatedDebenturesRBPIMergerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_JuniorSubordinatedDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=bmtc_RoyalBancsharesOfPennsylvaniaIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=bmtc_RoyalBancsharesCapitalTrustIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=bmtc_RoyalBancsharesCapitalTrustIIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=bmtc_RoyalBancsharesTrustIAndIIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Junior Subordinated Debentures (Details) - USD ($)	12 Months Ended
Junior Subordinated Debentures (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 15, 2017
Other investments	$ 17,742,000	$ 16,683,000
Royal Bancshares Capital Trust I
Trust, capital securities issued	12,500,000
Trust, common securities, issued	387,000
Royal Bancshares Capital Trust II
Trust, capital securities issued	12,500,000
Trust, common securities, issued	$ 387,000
Junior Subordinated Debentures, RBPI Merger \| Junior Subordinated Debt
Junior subordinated debentures interest rate	2.37%
Junior Subordinated Debentures, RBPI Merger \| Junior Subordinated Debt \| London Interbank Offered Rate (LIBOR)
Subordinated notes, basis spread on variable rate	2.15%
Royal Bancshares of Pennsylvania, Inc.
Junior subordinated debentures			$ 21,400,000
Royal Bancshares of Pennsylvania, Inc. \| Royal Bancshares Capital Trust I
Junior subordinated debentures			10,700,000
Royal Bancshares of Pennsylvania, Inc. \| Royal Bancshares Capital Trust II
Junior subordinated debentures			10,700,000
Royal Bancshares Capital Trust I and II
Other investments	$ 387,000		$ 774,000