Derivative Instruments (Maturity Of The Notional Amounts Of Derivative Financial Instruments) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year	$ 32,325
Remaining Life - 1 - 5 Years	23,641
Remaining Life - 6 - 10 Years	47,201
Remaining Life - 11 - 30 Years	20,660
Remaining Life Over - 30 Years	4,204
Remaining Life - Total Years	128,031
Interest rate contracts [Member]
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year	13,347	[1]
Remaining Life - 1 - 5 Years	14,517	[1]
Remaining Life - 6 - 10 Years	46,210	[1]
Remaining Life - 11 - 30 Years	19,533	[1]
Remaining Life Over - 30 Years	1,213	[1]
Remaining Life - Total Years	$ 94,820	[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	$ 165	[2]
Remaining Life - 1 - 5 Years	260	[2]
Remaining Life - 6 - 10 Years	601	[2]
Remaining Life - 11 - 30 Years	1,113	[2]
Remaining Life Over - 30 Years	23	[2]
Remaining Life - Total Years	$ 2,162	[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	$ 18,813
Remaining Life - 1 - 5 Years	8,864
Remaining Life - 6 - 10 Years	390
Remaining Life - 11 - 30 Years	14
Remaining Life Over - 30 Years	2,968
Remaining Life - Total Years	$ 31,049

[1] As of June 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 June 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.