Investments in Qualified Affordable Housing Partnerships - Narrative (Details) - USD ($)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2020
Business Acquisition [Line Items]
Period of tax credits	10 years
Amortization method investments in qualified affordable housing projects	$ 86,800,000	$ 49,900,000
Cost method investments in qualified affordable housing projects	3,000,000.0	4,000,000.0
Net investment in qualified affordable housing projects	89,800,000	53,900,000
Total unfunded commitments related to investments in qualified affordable housing funds	18,078,000	21,400,000
Impairment losses related to LIHTC investments	$ 0	$ 0	$ 0
Opus
Business Acquisition [Line Items]
Amortization method investments in qualified affordable housing projects				$ 45,400,000

Affordable Housing Projects, Tax Credit Period

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Amortization and Cost Method Qualified Affordable Housing Project Investments

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Amount of write-down from impairment of an investment in a qualified affordable housing project.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 740
-Section 50
-Paragraph 2
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=116633289&loc=SL49122993-202985

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Amount of investment in qualified affordable housing projects.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 740
-Section 50
-Paragraph 2
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Amount of commitment or contingent commitments to qualified affordable housing project investments.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 323
-SubTopic 740
-Section 50
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