Agreements and Related Party Transactions - Sub-Administration and Custody Agreement (Details) - State Street Sub-Administration Agreement and Custody Agreement	Oct. 01, 2018
Related Party Transaction [Line Items]
Related party transaction, initial term	2 years
Related party transaction, renewal term	1 year
Termination notice period	120 days

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details