Summary of Significant Accounting Policies - Schedule of Impact of Adoption for DAC (Details) $ in Millions	Dec. 31, 2020 USD ($)
Deferred Policy Acquisition Cost [Line Items]
Impact of adoption for DAC	$ 472
Pre-adoption balance
Deferred Policy Acquisition Cost [Line Items]
Impact of adoption for DAC	470
Adjustment for removal of impact of unrealized gains or losses
Deferred Policy Acquisition Cost [Line Items]
Impact of adoption for DAC	2
Accident and health
Deferred Policy Acquisition Cost [Line Items]
Impact of adoption for DAC	343
Accident and health | Pre-adoption balance
Deferred Policy Acquisition Cost [Line Items]
Impact of adoption for DAC	343
Accident and health | Adjustment for removal of impact of unrealized gains or losses
Deferred Policy Acquisition Cost [Line Items]
Impact of adoption for DAC	0
Traditional life
Deferred Policy Acquisition Cost [Line Items]
Impact of adoption for DAC	32
Traditional life | Pre-adoption balance
Deferred Policy Acquisition Cost [Line Items]
Impact of adoption for DAC	32
Traditional life | Adjustment for removal of impact of unrealized gains or losses
Deferred Policy Acquisition Cost [Line Items]
Impact of adoption for DAC	0
Interest- sensitive life
Deferred Policy Acquisition Cost [Line Items]
Impact of adoption for DAC	97
Interest- sensitive life | Pre-adoption balance
Deferred Policy Acquisition Cost [Line Items]
Impact of adoption for DAC	95
Interest- sensitive life | Adjustment for removal of impact of unrealized gains or losses
Deferred Policy Acquisition Cost [Line Items]
Impact of adoption for DAC	$ 2