Securities - Significant Assumptions (Details) - Non-agency residential	Jun. 30, 2019
Weighted Average
Significant Assumptions:
Prepayment speed	16.10%
Loss severity	15.90%
Life default rate	12.70%
Weighted Average \| Prime
Significant Assumptions:
Loss severity	12.60%
Life default rate	8.60%
Weighted Average \| Alt-A
Significant Assumptions:
Loss severity	11.90%
Life default rate	11.50%
Weighted Average \| Subprime
Significant Assumptions:
Loss severity	20.70%
Life default rate	15.50%
10th Percentile
Significant Assumptions:
Prepayment speed	4.80%
Loss severity	8.00%
Life default rate	0.90%
90th Percentile
Significant Assumptions:
Prepayment speed	27.90%
Loss severity	33.10%
Life default rate	41.70%