Derivative Instruments (Maturity Of The Notional Amounts Of Derivative Financial Instruments) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018 USD ($)
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year	$ 29,151
Remaining Life - 1 - 5 Years	18,673
Remaining Life - 6 - 10 Years	47,943
Remaining Life - 11 - 30 Years	21,262
Remaining Life Over - 30 Years	4,343
Remaining Life - Total Years	121,372
Interest rate contracts [Member]
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year	10,907	[1]
Remaining Life - 1 - 5 Years	14,802	[1]
Remaining Life - 6 - 10 Years	47,193	[1]
Remaining Life - 11 - 30 Years	20,118	[1]
Remaining Life Over - 30 Years	1,213	[1]
Remaining Life - Total Years	$ 94,233	[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	$ 141	[2]
Remaining Life - 1 - 5 Years	256	[2]
Remaining Life - 6 - 10 Years	635	[2]
Remaining Life - 11 - 30 Years	1,130	[2]
Remaining Life Over - 30 Years	10	[2]
Remaining Life - Total Years	$ 2,172	[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	$ 18,103
Remaining Life - 1 - 5 Years	3,615
Remaining Life - 6 - 10 Years	115
Remaining Life - 11 - 30 Years	14
Remaining Life Over - 30 Years	3,120
Remaining Life - Total Years	$ 24,967

[1] As of September 30, 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 September 30, 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.