Derivatives and Hedging Activites (Option Pay/Rec) (Details 3) $ in Millions	Mar. 31, 2021 USD ($)
Summary of Option Premiums Payable and Receivable
Premiums payable	$ 893
Premiums receivable	467
2021 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	112	[1]
Premiums receivable	85	[1]
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	42
2024 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	138
Premiums receivable	25
2025 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	125
Premiums receivable	22
2026-2028 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	262
Premiums receivable	$ 88

[1] 2021 amounts represent the amounts payable and receivable for the period from April 1, 2021 to December 31, 2021.