| **Non-Insurance Revenues from Contracts with Customers (Performance obligation) (Details) $ in Billions** | Jun. 30, 2024 USD ($) |
|-----------------------------------------------------------------------------------------------------------|-----------------------|
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01 |                  |
| **Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]**               |                  |
| Remaining performance obligation, amount                                                                  | $ 0.8                 |
| Remaining performance obligation, expected timing of satisfaction, period                                 | 6 months              |
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01 |                  |
| **Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]**               |                  |
| Remaining performance obligation, amount                                                                  | $ 1.2                 |
| Remaining performance obligation, expected timing of satisfaction, period                                 | 1 year                |
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01 |                  |
| **Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]**               |                  |
| Remaining performance obligation, amount                                                                  | $ 0.9                 |
| Remaining performance obligation, expected timing of satisfaction, period                                 | 1 year                |
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01 |                  |
| **Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]**               |                  |
| Remaining performance obligation, amount                                                                  | $ 1.7                 |
| Remaining performance obligation, expected timing of satisfaction, period                                 |                       |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of transaction price allocated to performance obligation that has not been recognized as revenue.
+ References
Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (a) -SubTopic 10 -Topic 606 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479806/606-10-50-13
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
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.
+ References
No definition available.
+ Details**Name:**us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Period in which remaining performance obligation is expected to be recognized as revenue, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.
+ References
Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (b)(1) -SubTopic 10 -Topic 606 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479806/606-10-50-13
+ Details**Name:**us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1**Namespace Prefix:**us-gaap_**Data Type:**xbrli:durationItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis=2025-01-01**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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