Business, Basis of Presentation and Summary of Significant Accounting Policies -Upper-Medium Grade Discount Rate (Details)	Dec. 31, 2024
JAPAN
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Liability For Future Policy Benefit, Upper-Medium Grade Discount Rate, Measurement Input	10
Republic of Korea
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Liability For Future Policy Benefit, Upper-Medium Grade Discount Rate, Measurement Input	5
CHILE
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Liability For Future Policy Benefit, Upper-Medium Grade Discount Rate, Measurement Input	10
Measurement Input, Credit Spread | JAPAN | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Liability For Future Policy Benefit, Upper-Medium Grade Discount Rate, Measurement Input	10
Measurement Input, Credit Spread | JAPAN | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Liability For Future Policy Benefit, Upper-Medium Grade Discount Rate, Measurement Input	30
Measurement Input, Credit Spread | Republic of Korea | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Liability For Future Policy Benefit, Upper-Medium Grade Discount Rate, Measurement Input	5
Measurement Input, Credit Spread | Republic of Korea | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Liability For Future Policy Benefit, Upper-Medium Grade Discount Rate, Measurement Input	30
Measurement Input, Credit Spread | CHILE | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Liability For Future Policy Benefit, Upper-Medium Grade Discount Rate, Measurement Input	10
Measurement Input, Credit Spread | CHILE | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Liability For Future Policy Benefit, Upper-Medium Grade Discount Rate, Measurement Input	25