Loans and the Allowance for Loan Losses - Loans Receivable Disaggregated by Credit Quality Indicator (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable Recorded Investment [Line Items]
Loans receivable	$ 2,096,550	$ 1,559,772
Residential Mortgage
Financing Receivable Recorded Investment [Line Items]
Loans receivable	938,559	604,331
Residential Mortgage | Performing
Financing Receivable Recorded Investment [Line Items]
Loans receivable	937,947	603,708
Residential Mortgage | Non-Performing Loans
Financing Receivable Recorded Investment [Line Items]
Loans receivable	612	623
Home Equity
Financing Receivable Recorded Investment [Line Items]
Loans receivable	85,814	69,336
Home Equity | Performing
Financing Receivable Recorded Investment [Line Items]
Loans receivable	85,802	69,323
Home Equity | Non-Performing Loans
Financing Receivable Recorded Investment [Line Items]
Loans receivable	12	13
Consumer
Financing Receivable Recorded Investment [Line Items]
Loans receivable	32,428	34,436
Consumer | Performing
Financing Receivable Recorded Investment [Line Items]
Loans receivable	32,428	34,436
Commercial Mortgage
Financing Receivable Recorded Investment [Line Items]
Loans receivable	905,442	757,957
Commercial Mortgage | 1-6 (Pass)
Financing Receivable Recorded Investment [Line Items]
Loans receivable	895,336	753,338
Commercial Mortgage | 7 (Special Mention)
Financing Receivable Recorded Investment [Line Items]
Loans receivable	9,571	4,619
Commercial Mortgage | 8 (Substandard)
Financing Receivable Recorded Investment [Line Items]
Loans receivable	535
Commercial & Industrial
Financing Receivable Recorded Investment [Line Items]
Loans receivable	134,307	93,712
Commercial & Industrial | 1-6 (Pass)
Financing Receivable Recorded Investment [Line Items]
Loans receivable	125,763	85,821
Commercial & Industrial | 7 (Special Mention)
Financing Receivable Recorded Investment [Line Items]
Loans receivable	3,487	4,186
Commercial & Industrial | 8 (Substandard)
Financing Receivable Recorded Investment [Line Items]
Loans receivable	$ 5,057	$ 3,705