Investments (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
U.S. Equity Cumulative Dividends Fund-Series 2027 | Long futures contracts [Member]
Offsetting Liabilities [Line Items]
Derivative, Notional Amount	$ 18,625,830	$ 5,394,216
U.S. Equity Ex-Dividend Fund-Series 2027 | Long futures contracts [Member]
Offsetting Liabilities [Line Items]
Derivative, Notional Amount	24,515,948	17,024,158
U.S. Equity Ex-Dividend Fund-Series 2027 | Short futures contracts [Member]
Offsetting Liabilities [Line Items]
Derivative, Notional Amount	$ (4,836,952)	$ (3,872,892)