Counterparty Risk (% of Due from Brokers) (Details) |
12 Months Ended | |
|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
|
| Concentration Risk [Line Items] | ||
| Concentration risk threshold | 15.00% | 15.00% |
| Morgan Stanley [Member] | ||
| Concentration Risk [Line Items] | ||
| % of Total Due from Brokers | 37.00% | |
| J.P. Morgan Securities LLC [Member] | ||
| Concentration Risk [Line Items] | ||
| % of Total Due from Brokers | 30.00% | |