Parent Company - Only Financial Statements - Condensed Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Income Statements, Captions [Line Items]
Dividends									$ 5	$ 6	$ 6
Income before equity in undistributed income of subsidiaries									41,354	74,803	77,957
Income before income taxes	$ 19,628	$ 16,833	$ 19,013	$ (14,120)	$ 20,585	$ 20,761	$ 20,017	$ 13,440	41,354	74,803	77,957
Income tax (benefit) expense	4,094	3,709	4,010	(2,957)	4,202	4,402	4,239	2,764	8,856	15,607	14,165
Net income attributable to Bryn Mawr Bank Corporation	$ 15,537	$ 13,164	$ 15,035	$ (11,163)	$ 16,384	$ 16,360	$ 15,785	$ 10,677	32,573	59,206	63,792
Parent Company
Condensed Income Statements, Captions [Line Items]
Dividends									40,223	35,731	30,900
Net interest and other income									8,311	10,962	2,615
Total operating income									48,534	46,693	33,515
Expenses									6,210	10,517	3,527
Income before equity in undistributed income of subsidiaries									42,324	36,176	29,988
Equity in undistributed income of subsidiaries									(9,144)	23,048	32,779
Income before income taxes									33,180	59,224	62,767
Income tax (benefit) expense									607	18	(1,025)
Net income attributable to Bryn Mawr Bank Corporation									$ 32,573	$ 59,206	$ 63,792