Loans, net and allowance for loan losses - Major Classifications of Loans Outstanding (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable
Loans	$ 2,181,909	$ 1,938,240
Commercial
Accounts, Notes, Loans and Financing Receivable
Loans	694,551	522,957
Real estate Commercial
Accounts, Notes, Loans and Financing Receivable
Loans	1,099,818	1,011,423
Real estate Residential
Accounts, Notes, Loans and Financing Receivable
Loans	297,880	301,378
Consumer
Accounts, Notes, Loans and Financing Receivable
Loans	$ 89,660	$ 102,482

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5074-111524

Name:	us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant