Off-Balance-Sheet Arrangements, Allowance for off-balance-sheet credit exposures (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Balance at beginning of period	$ 6,365	$ 1,859	$ 1,455	$ 1,890
Provision for (reversal of) off-balance-sheet credit exposures	(345)	(319)	(275)	(350)
Balance at end of period	6,020	1,540	6,020	1,540
Impact of CECL adoption
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Balance at beginning of period	$ 0	$ 0	$ 4,840	$ 0

Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121611286&loc=d3e11927-110247

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82919202-210446

Name:	us-gaap_OffBalanceSheetCreditLossLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant