Business Combinations - Due Diligence, Merger-related and Merger Integration Costs (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Business Combinations [Abstract]
Advertising	$ 0	$ 59
Employee Benefits	0	203
Occupancy and bank premises	0	1,856
Furniture, fixtures, and equipment	0	179
Data processing	0	112
Professional fees	0	747
Salaries and wages	0	346
Other	0	817
Total due diligence, merger-related and merger integration expenses	$ 0	$ 4,319

The adverting costs incurred to effect a business combination which have been expensed during the period.

No definition available.

Name:	bmtc_BusinessCombinationIntegrationRelatedCostsAdvertising
Namespace Prefix:	bmtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Business Combination, Integration Related Costs, Data Processing

+ References

No definition available.

+ Details

Name:	bmtc_BusinessCombinationIntegrationRelatedCostsDataProcessing
Namespace Prefix:	bmtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The furniture, fixture and equipment costs incurred to effect a business combination which have been expensed during the period.

+ References

No definition available.

+ Details

Name:	bmtc_BusinessCombinationIntegrationRelatedCostsFurnitureFixturesAndEquipment
Namespace Prefix:	bmtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The occupancy and bank premises costs incurred to effect a business combination which have been expensed during the period.

+ References

No definition available.

+ Details

Name:	bmtc_BusinessCombinationIntegrationRelatedCostsOccupancyAndBankPremises
Namespace Prefix:	bmtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The other costs incurred to effect a business combination which have been expensed during the period.

+ References

No definition available.

+ Details

Name:	bmtc_BusinessCombinationIntegrationRelatedCostsOther
Namespace Prefix:	bmtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The professional fees incurred to effect a business combination which have been expensed during the period.

+ References

No definition available.

+ Details

Name:	bmtc_BusinessCombinationIntegrationRelatedCostsProfessionalFees
Namespace Prefix:	bmtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The salaries and wages incurred to effect a business combination which have been expensed during the period.

+ References

No definition available.

+ Details

Name:	bmtc_BusinessCombinationIntegrationRelatedCostsSalariesAndWages
Namespace Prefix:	bmtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The employee benefit costs incurred to effect a business combination which have been expensed during the period.

+ References

No definition available.

+ Details

Name:	bmtc_BusinessCombinationIntergrationRelatedCostsEmployeeBenefits
Namespace Prefix:	bmtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Costs incurred to effect a business combination which have been expensed during the period. Such costs could include business integration costs, systems integration and conversion costs, and severance and other employee-related costs.

+ References

No definition available.

+ Details

Name:	us-gaap_BusinessCombinationIntegrationRelatedCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

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