Financial Derivatives (Schedule of Credit Derivatives) (Details) - USD ($) $ in Thousands |
Mar. 31, 2020 |
Dec. 31, 2019 |
|---|---|---|
| Credit Default Swap, Selling Protection [Member] | ||
| Credit Derivatives [Line Items] | ||
| Fair Value | $ (1,992) | $ 5,414 |
| Notional value | 74,024 | 132,176 |
| Credit Default Swap, Buying Protection [Member] | ||
| Credit Derivatives [Line Items] | ||
| Fair Value of Purchased Credit Derivatives Offsetting Written Credit Derivatives | 0 | (3,248) |
| Notional value of purchased credit derivatives offsetting written credit derivatives | $ 0 | $ (81,637) |