Derivatives and Hedging Activites (Option Pay/Rec) (Details 4) $ in Millions		Jun. 30, 2015 USD ($)
Summary of Option Premiums Payable and Receivable
Premiums payable		$ 1,927
Premiums receivable		612
Current Year [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable	[1]	194
Premiums receivable	[1]	38
2016 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable		346
Premiums receivable		77
2017 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable		276
Premiums receivable		77
2018 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable		216
Premiums receivable		125
2019 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable		261
Premiums receivable		87
2020-2027 [Member]
Summary of Option Premiums Payable and Receivable
Premiums payable		634
Premiums receivable		$ 208

[1] 2015 amounts represent the amounts payable and receivable for the period from July 1, 2015 to December 31, 2015.