Accumulated Other Comprehensive (Loss) Income - Amounts Reclassified From Each Component of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other operating expenses	$ 4,548	$ 4,985	$ 9,162	$ 8,302
Income tax expense	4,239	3,723	7,003	8,353
Net income attributable to Bryn Mawr Bank Corporation	15,785	14,688	26,462	29,974
Other operating income	3,052	3,034	5,899	7,372
Income before income taxes	20,017	18,418	33,457	38,333
Amount Reclassified from Accumulated Other Comprehensive Loss | Net Change in Unrealized Gains on Available-for- Sale Investment Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Income tax expense			0	89
Net income attributable to Bryn Mawr Bank Corporation			0	(335)
Realization of gain on sale of investment securities available for sale			0	(7)
Other operating income			0	(417)
Income before income taxes			0	(424)
Amount Reclassified from Accumulated Other Comprehensive Loss | Net Change in Unfunded Pension Liability
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other operating expenses	13	25	24	50
Income tax expense	(3)	(5)	(5)	(10)
Net income attributable to Bryn Mawr Bank Corporation	$ 10	$ 20	$ 19	$ 40