Derivatives and Hedging Activites (Option Pay/Rec) (Details 3) $ in Millions	Sep. 30, 2020 USD ($)
Summary of Option Premiums Payable and Receivable
Premiums payable	$ 962
Premiums receivable	390
2020 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	35	[1]
Premiums receivable	4	[1]
2021 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	152
Premiums receivable	106
2022 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	205
Premiums receivable	205
2023 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	51
Premiums receivable	43
2024 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	140
Premiums receivable	25
2025-2028 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	379
Premiums receivable	$ 7

[1] 2020 amounts represent the amounts payable and receivable for the period from October 1, 2020 to December 31, 2020.