Summary of Significant Accounting Policies - Narrative (Details) $ in Millions	12 Months Ended
Dec. 31, 2022 USD ($) subsidiary segment	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Accounting Policies [Abstract]
Number of subsidiaries \| subsidiary	2
Mortgage loans with an aggregate outstanding principal balance	$ 299.4	$ 299.4
Number of operating segments \| segment	7
Percentage of class A securities back by pool in structured securitization	92.50%
Percentage of class B securities back by pool in structured securitization	7.50%
Gain on securitization of financial assets		6.5
Compensation expense	$ 4.6	$ 4.3	$ 4.1

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Percentage Of Class A Securities Back By Pool In Structured Securitization

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Percentage Of Class B Securities Back By Pool In Structured Securitization

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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A gain (loss) realized on a transfer, accounted for as a sale, of all or a portion of financial assets in which the transferor surrenders control and receives consideration other than a beneficial interest in the assets transferred. Reflects the amount of sales proceeds in excess of, or deficient from, the sum of the carrying amounts of transferred financial assets plus transaction costs.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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This is the principal amount outstanding for securitized loans only (across all types of loans).

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