Derivative Instruments - Collateral by Counterparty (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Derivatives Assets and Liabilities Collateral Received by Counterparty
Net Amount of Unrealized Gain Presented in the Consolidated Statement of Financial Condition	$ 3,574,801	$ 3,849,598
Net Amount	3,574,801	3,849,598
ADM Investor Services, Inc.
Derivatives Assets and Liabilities Collateral Received by Counterparty
Net Amount of Unrealized Gain Presented in the Consolidated Statement of Financial Condition	230,586
Net Amount	230,586
Deutsche Bank AG
Derivatives Assets and Liabilities Collateral Received by Counterparty
Net Amount of Unrealized Gain Presented in the Consolidated Statement of Financial Condition	1,598,794	1,179,312
Net Amount	1,598,794	1,179,312
SG Americas Securities, LLC
Derivatives Assets and Liabilities Collateral Received by Counterparty
Net Amount of Unrealized Gain Presented in the Consolidated Statement of Financial Condition	1,847,870	1,805,261
Net Amount	1,847,870	1,805,261
UBS AG
Derivatives Assets and Liabilities Collateral Received by Counterparty
Net Amount of Unrealized Gain Presented in the Consolidated Statement of Financial Condition	(102,449)	(60,011)
Net Amount	$ (102,449)	(60,011)
Wells Fargo Securities LLC
Derivatives Assets and Liabilities Collateral Received by Counterparty
Net Amount of Unrealized Gain Presented in the Consolidated Statement of Financial Condition		925,036
Net Amount		$ 925,036