Commercial Mortgage Loans Held for Investment - Summary of Investment Grade of Loans Loss (Details) - Commercial Mortgage Loans	9 Months Ended
	Sep. 30, 2022
Investment Grade One
Financing Receivable Recorded Investment [Line Items]
Description of Investment Grade	Investment exceeding fundamental performance expectations and/or capital gain expected. Trends and risk factors since time of investment are favorable.
Investment Grade Two
Financing Receivable Recorded Investment [Line Items]
Description of Investment Grade	Performing consistent with expectations and a full return of principal and interest expected. Trends and risk factors are neutral to favorable.
Investment Grade Three
Financing Receivable Recorded Investment [Line Items]
Description of Investment Grade	Performing investment requiring closer monitoring. Trends and risk factors show some deterioration. Collection of principal and interest is still expected.
Investment Grade Four
Financing Receivable Recorded Investment [Line Items]
Description of Investment Grade	Underperforming investment with the potential of some interest loss but still expecting a positive return on investment. Trends and risk factors are negative.
Investment Grade Five
Financing Receivable Recorded Investment [Line Items]
Description of Investment Grade	Underperforming investment with expected loss of interest and some principal.