Derivative Instruments (Maturity Of The Notional Amounts Of Derivative Financial Instruments) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year	$ 44,423
Remaining Life - 1 - 5 Years	22,500
Remaining Life - 6 - 10 Years	46,751
Remaining Life - 11 - 30 Years	19,434
Remaining Life Over - 30 Years	3,887
Remaining Life - Total Years	136,995
Interest rate contracts [Member]
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year	25,386	[1]
Remaining Life - 1 - 5 Years	13,592	[1]
Remaining Life - 6 - 10 Years	45,940	[1]
Remaining Life - 11 - 30 Years	18,259	[1]
Remaining Life Over - 30 Years	1,213	[1]
Remaining Life - Total Years	$ 104,390	[1]
Derivative maturity date	Apr. 01, 2067
Foreign currency contracts [Member]
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year	$ 114	[2]
Remaining Life - 1 - 5 Years	290	[2]
Remaining Life - 6 - 10 Years	426	[2]
Remaining Life - 11 - 30 Years	1,161	[2]
Remaining Life Over - 30 Years	10	[2]
Remaining Life - Total Years	$ 2,001	[2]
Derivative maturity date	Sep. 01, 2049
Equity market contracts [Member]
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year	$ 18,923
Remaining Life - 1 - 5 Years	8,618
Remaining Life - 6 - 10 Years	385
Remaining Life - 11 - 30 Years	14
Remaining Life Over - 30 Years	2,664
Remaining Life - Total Years	$ 30,604

[1] As of March 31, 2018, the latest maturity date for which we were hedging our exposure to the variability in future cash flows for these instruments was April 2067.

[2] As of March 31, 2018, the latest maturity date for which we were hedging our exposure to the variability in future cash flows for these instruments was September 2049.