Business Combinations - Pro Forma Income Statements (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Total interest income	$ 44,754	$ 31,237	$ 88,288	$ 61,563
Total interest expense	7,438	3,272	13,533	6,195
Net interest income	37,316	27,965	74,755	55,368
Net interest income after provision for loan and lease losses	34,179	28,048	70,588	55,160
Total noninterest income	20,075	14,785	39,611	28,012
Total non-interest expense	35,836	28,495	71,866	55,155
Income before income taxes	18,418	14,338	38,333	28,017
Income tax expense	3,723	4,905	8,353	9,540
Net income attributable to Bryn Mawr Bank Corporation	$ 14,688	$ 9,433	$ 29,974	$ 18,477
Weighted-average basic shares outstanding (in shares)	20,238,852	16,984,563	20,221,010	16,969,431
Dilutive shares	174,726	248,204	206,782	238,381
Denominator for diluted earnings per share – adjusted weighted average shares outstanding	20,413,578	17,232,767	20,427,792	17,207,812
Basic earnings per share (in dollars per share)	$ 0.73	$ 0.56	$ 1.48	$ 1.09
Diluted earnings per share (in dollars per share)	$ 0.72	$ 0.55	$ 1.47	$ 1.07
Pro Forma
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Total interest income		$ 42,337		$ 83,564
Total interest expense		4,971		9,533
Net interest income		37,366		74,031
Provision for loan and lease losses		(26)		562
Net interest income after provision for loan and lease losses		37,392		73,469
Total noninterest income		15,728		29,466
Total non-interest expense		34,040		66,335
Income before income taxes		19,080		36,600
Income tax expense		6,526		12,463
Net income attributable to Bryn Mawr Bank Corporation		$ 12,554		$ 24,137
Weighted-average basic shares outstanding (in shares)		20,083,317		20,068,185
Dilutive shares		278,199		267,210
Denominator for diluted earnings per share – adjusted weighted average shares outstanding		20,361,516		20,335,395
Basic earnings per share (in dollars per share)		$ 0.63		$ 1.20
Diluted earnings per share (in dollars per share)		$ 0.62		$ 1.19