Securities - Summary of Activity in Allowance for Credit Losses for Held To Maturity Debt Securities (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2020
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses beginning balance		$ 0
Allowance for credit losses ending balance	$ 1,961	1,961
CLO securities
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses beginning balance	1,855	0
Credit loss expense	106	1,835
Allowance for credit losses ending balance	1,961	1,961
ASU 2016-13 \| CLO securities
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Impact of adopting ASC 326	$ 0	$ 126

Amount of allowance for credit loss for debt security measured at amortized cost (held-to-maturity).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aaa)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118955202&loc=SL82895884-210446

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Amount of expense (reversal of expense) for expected credit loss on investment in debt security measured at amortized cost (held-to-maturity).

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- Definition

Represents the quantification of the effect of adopting the new accounting standard or change in accounting principle expected by the entity to have a significant effect on the entity's financial statements.

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