Commitments and Contingencies (Details) - USD ($) |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
|---|---|---|---|
| Other Commitments [Line Items] | |||
| Guarantor Obligations, Current Carrying Value | $ 1,000,000.0 | ||
| Related party mortgage originator (with flow mortgage loan purchase and sale agreement) [Member] | Non-Exchange Traded Equity Investment in Mortgage Originators [Member] | |||
| Other Commitments [Line Items] | |||
| Maximum guarantees | $ 25,000,000.0 | ||
| Drawn down amount being guaranteed | 5,300,000 | $ 400,000 | 2,900,000 |
| Guarantor Obligations, Current Carrying Value | 0 | ||
| Guaranty Liabilities | $ 25,000,000.0 | ||
| Residential mortgage loans | |||
| Other Commitments [Line Items] | |||
| Unfunded commitment | 4,700,000 | 5,200,000 | |
| Corporate loan [Member] | |||
| Other Commitments [Line Items] | |||
| Unfunded commitment | $ 100,000 | $ 1,900,000 |