Derivative Financial Instruments - OTC derivatives counterparty credit exposure by counterparty credit rating (Details) $ in Millions	Jun. 30, 2023 USD ($) counter-party	Dec. 31, 2022 USD ($) counter-party
Credit Derivatives
Number of counter- parties | counter-party	1	2
Notional amount	$ 199	$ 320
Credit exposure	2	12
Exposure, net of collateral	$ 0	$ 0
A+
Credit Derivatives
Number of counter- parties | counter-party	1	1
Notional amount	$ 199	$ 128
Credit exposure	2	5
Exposure, net of collateral	$ 0	$ 0
A
Credit Derivatives
Number of counter- parties | counter-party	0	1
Notional amount	$ 0	$ 192
Credit exposure	0	7
Exposure, net of collateral	$ 0	$ 0