Investment Securities - Carrying value of other investment securities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Other investment securities
Carrying Value	$ 62,994	$ 49,124	$ 40,624
Investment in Federal Home Loan Bank Stock
Other investment securities
Carrying Value	56,914	43,044	34,544
Investment in unconsolidated subsidiaries
Other investment securities
Carrying Value	3,563	3,563	3,563
Other nonmarketable investment securities
Other investment securities
Carrying Value	$ 2,517	$ 2,517	$ 2,517

Amount of investments classified as other.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(f,g))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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