| Standard label: | Guaranteed Minimum Income Benefit [Member] |
| Name: | us-gaap:GuaranteedMinimumIncomeBenefitMember |
| Documentation: | Feature in an insurance contract that provides a guaranteed minimum amount available for annuitization after a specified period, which is in addition to a guaranteed minimum annuity rate. |
| Object type: | cm:Member |
| Data type: | [Member] (nonnum:domainItemType) |
| Period type: | For Period (duration) |
| Balance type: | (no balance type) |
| Abstract: | true |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:GuaranteedMinimumIncomeBenefitMember |
| Label | Role | Language |
| Guaranteed Minimum Income Benefit [Member] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 944 20 55 15 | http://fasb.org/us-gaap/role/ref/legacyRef | 944 |
| FASB Accounting Standards Codification 944 40 50 7B | http://www.xbrl.org/2009/role/commonPracticeRef | 944 |
| FASB Accounting Standards Codification 944 80 50 1 (d)(1)(b) | http://fasb.org/us-gaap/role/ref/legacyRef | 944 |