Loans Receivable and Related Allowance for Loan Losses - Types of Loans by Industry Sector (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($) loan
Commercial and Industrial Sector [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans | loan	2,386
Balance | $	$ 432,460
Real Estate Rental and Leasing
Financing Receivable, Recorded Investment [Line Items]
Number of loans | loan	1,281
Balance | $	$ 273,820
Construction
Financing Receivable, Recorded Investment [Line Items]
Number of loans | loan	165
Balance | $	$ 26,908
Accommodation and Food Services
Financing Receivable, Recorded Investment [Line Items]
Number of loans | loan	72
Balance | $	$ 23,618
Other Services (except Public Administration)
Financing Receivable, Recorded Investment [Line Items]
Number of loans | loan	141
Balance | $	$ 15,868
Health Care and Social Assistance
Financing Receivable, Recorded Investment [Line Items]
Number of loans | loan	117
Balance | $	$ 15,645
Retail Trade
Financing Receivable, Recorded Investment [Line Items]
Number of loans | loan	88
Balance | $	$ 14,854
Manufacturing
Financing Receivable, Recorded Investment [Line Items]
Number of loans | loan	48
Balance | $	$ 12,418
Professional, Scientific, and Technical Services
Financing Receivable, Recorded Investment [Line Items]
Number of loans | loan	131
Balance | $	$ 10,622
Wholesale Trade
Financing Receivable, Recorded Investment [Line Items]
Number of loans | loan	58
Balance | $	$ 7,743
Finance and Insurance
Financing Receivable, Recorded Investment [Line Items]
Number of loans | loan	41
Balance | $	$ 7,391
Other
Financing Receivable, Recorded Investment [Line Items]
Number of loans | loan	244
Balance | $	$ 23,573