Mortgage-Backed Securities - Percentage of Non-Agency RMBS By Year Originated (Details) - Non-Agency RMBS	Jun. 30, 2023	Dec. 31, 2022
Origination Year as a Percentage of Outstanding Principal Balance:
2003 and prior	0.70%	0.70%
2004	1.10%	1.10%
2005	8.60%	9.00%
2006	45.00%	45.00%
2007	31.40%	30.80%
2008 and later	13.20%	13.40%
Total	100.00%	100.00%