| Standard label: | Site Contingency, Time Frame of Disbursements |
| Name: | us-gaap:SiteContingencyTimeFrameOfDisbursements |
| Documentation: | Estimated time frame of disbursements over which the accrued or presently unrecognized amounts may be paid out for an individual site. |
| Object type: | cm:Concept |
| Data type: | Text/String (xbrli:stringItemType) |
| Period type: | For Period (duration) |
| Balance type: | (no balance type) |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:SiteContingencyTimeFrameOfDisbursements |
| Label | Role | Language |
| Site Contingency, Time Frame of Disbursements | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 410 30 50 10 (a) | http://fasb.org/us-gaap/role/ref/legacyRef | 410 |
| FASB Accounting Standards Codification 450 20 S99 1 (SAB TOPIC 5.Y.Q2) | http://fasb.org/us-gaap/role/ref/legacyRef | 450 |
| FASB Accounting Standards Codification 450 20 S99 1 (SAB Topic 5.Y.Q4) | http://fasb.org/us-gaap/role/ref/legacyRef | 450 |