| Name | USTreasuryBillSecuritiesMember |
|---|---|
| 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 |
|---|---|---|---|
| This category includes information about negotiable debt securities issued by the United States Department of the Treasury which generally have maturities of one year or less, are interest bearing, and are backed by the full faith and credit of the United States government. | en-US | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |
| US Treasury Bill Securities [Member] | en-US | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Name | Value | Role |
|---|---|---|
| Publisher | FASB | http://www.xbrl.org/2009/role/commonPracticeRef |
| Name | Accounting Standards Codification | http://www.xbrl.org/2009/role/commonPracticeRef |
| Topic | 942 | http://www.xbrl.org/2009/role/commonPracticeRef |
| SubTopic | 320 | http://www.xbrl.org/2009/role/commonPracticeRef |
| Section | 50 | http://www.xbrl.org/2009/role/commonPracticeRef |
| Paragraph | 2 | http://www.xbrl.org/2009/role/commonPracticeRef |
| Subparagraph | (b) | http://www.xbrl.org/2009/role/commonPracticeRef |
| URI | http://asc.fasb.org/extlink&oid=120252992&loc=d3e62557-112803 | http://www.xbrl.org/2009/role/commonPracticeRef |