Derivatives and Hedging Activites (Option Pay/Rec) (Details 3) $ in Millions	Jun. 30, 2019 USD ($)
Summary of Option Premiums Payable and Receivable
Premiums payable	$ 1,391
Premiums receivable	648
2019 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	203	[1]
Premiums receivable	126	[1]
2020 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	216
Premiums receivable	135
2021 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	187
Premiums receivable	127
2022 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	222
Premiums receivable	200
2023 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	142
Premiums receivable	43
2024-2028 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	421
Premiums receivable	$ 17

[1] 2019 amounts represent the amounts payable and receivable for the period from July 1, 2019 to December 31, 2019.