Regulatory Capital Requirements - Capital Amounts and Ratios (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total (Tier II) capital to risk weighted assets, actual, amount	$ 500,375	$ 464
Total (Tier II) capital to risk weighted assets, actual, ratio	14.30%	13.92%
Total (Tier II) capital to risk weighted assets, minimum to be well capitalized, amount	$ 349,918	$ 333,068
Total (Tier II) capital to risk weighted assets, minimum to be well capitalized, ratio	10.00%	10.00%
Tier I capital to risk weighted assets, actual, amount	$ 382,151	$ 347
Tier I capital to risk weighted assets, actual, ratio	10.92%	10.42%
Tier I capital to risk weighted assets, minimum to be well capitalized, amount	$ 279,934	$ 266,454
Tier I capital to risk weighted assets, minimum to be well capitalized, ratio	8.00%	8.00%
Common equity tier I capital to risk weighted assets, actual, amount	$ 361,256	$ 329
Common equity tier I capital to risk weighted assets, actual, ratio	10.32%	9.87%
Common equity tier I capital to risk weighted assets, minimum to be well capitalized, amount	$ 227,446	$ 216,494
Common equity tier I capital to risk weighted assets, minimum to be well capitalized, ratio	6.50%	6.50%
Tier I capital to average assets, actual, amount	$ 382,151	$ 347
Tier I capital to average assets, actual, ratio	9.06%	10.10%
Tier I capital to average assets, minimum to be well capitalized, amount	$ 210,830	$ 171,804
Tier I capital to average assets, minimum to be well capitalized, ratio	5.00%	5.00%
Bryn Mawr Trust Company
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total (Tier II) capital to risk weighted assets, actual, amount	$ 419,136	$ 387,067
Total (Tier II) capital to risk weighted assets, actual, ratio	11.99%	11.65%
Total (Tier II) capital to risk weighted assets, minimum to be well capitalized, amount	$ 349,692	$ 332,388
Total (Tier II) capital to risk weighted assets, minimum to be well capitalized, ratio	10.00%	10.00%
Tier I capital to risk weighted assets, actual, amount	$ 399,438	$ 369,033
Tier I capital to risk weighted assets, actual, ratio	11.42%	11.10%
Tier I capital to risk weighted assets, minimum to be well capitalized, amount	$ 279,754	$ 265,910
Tier I capital to risk weighted assets, minimum to be well capitalized, ratio	8.00%	8.00%
Common equity tier I capital to risk weighted assets, actual, amount	$ 399,438	$ 369,033
Common equity tier I capital to risk weighted assets, actual, ratio	11.42%	11.10%
Common equity tier I capital to risk weighted assets, minimum to be well capitalized, amount	$ 227,300	$ 216,052
Common equity tier I capital to risk weighted assets, minimum to be well capitalized, ratio	6.50%	6.50%
Tier I capital to average assets, actual, amount	$ 399,438	$ 369,033
Tier I capital to average assets, actual, ratio	9.48%	10.75%
Tier I capital to average assets, minimum to be well capitalized, amount	$ 210,615	$ 171,609
Tier I capital to average assets, minimum to be well capitalized, ratio	5.00%	5.00%