| Name | CommodityIndexLinkedNotesMember |
|---|---|
| Namespace | http://fasb.org/us-gaap/2020-01-31 |
| Prefix | us-gaap |
| Data type | nonnum:domainItemType |
| Period type | duration |
| Substitution Group | xbrli:item |
| Balance | None |
| Nillable | True |
| Abstract | True |
| Text | Lang | Role | Container role |
|---|---|---|---|
| Commodity Index Linked Notes [Member] | en-US | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Investments in commodity index linked notes which are generally a composite investment consisting of an interest-bearing note (strip bond) and a long-term put or call option for an equity security or commodity contract. | en-US | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |