Contracts Accounted for as Credit Derivatives - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) Counterparty	Dec. 31, 2020 USD ($) Transaction
Credit Derivatives
Estimated remaining weighted average life of credit derivatives (in years)	13 years 2 months 12 days	11 years 10 months 24 days
Collateral Debt Obligations, Credit Derivative Contracts, Gross Par with Collateral Posting Requirements
Credit Derivatives
Derivative, number of counterparties | Counterparty	1
Derivative, notional amount	$ 18
Collateral Debt Obligations, Maximum Posting Requirement
Credit Derivatives
Derivative, notional amount	$ 18
Credit Default Swap
Credit Derivatives
Percentage of CDS contracts which are fair valued using minimum premium		51.00%
Number of transactions | Transaction		2
Net par outstanding value at floor		$ 2,400