Derivative Instruments (Maturity Of The Notional Amounts Of Derivative Financial Instruments) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year		$ 27,126
Remaining Life - 1 - 5 Years		35,024
Remaining Life - 6 - 10 Years		25,382
Remaining Life - 11 - 30 Years		15,048
Remaining Life Over - 30 Years		2,346
Remaining Life - Total Years		104,926	$ 105,333
Interest rate contracts [Member]
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year	[1]	11,102
Remaining Life - 1 - 5 Years	[1]	25,530
Remaining Life - 6 - 10 Years	[1]	23,164
Remaining Life - 11 - 30 Years	[1]	14,345
Remaining Life Over - 30 Years	[1]	1,213
Remaining Life - Total Years	[1]	$ 75,354
Derivative maturity date		Apr. 20, 2067
Foreign currency contracts [Member]
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year	[2]	$ 50
Remaining Life - 1 - 5 Years	[2]	109
Remaining Life - 6 - 10 Years	[2]	346
Remaining Life - 11 - 30 Years	[2]	686
Remaining Life Over - 30 Years	[2]
Remaining Life - Total Years	[2]	$ 1,191
Derivative maturity date		Dec. 10, 2045
Equity market contracts [Member]
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year		$ 15,924
Remaining Life - 1 - 5 Years		9,369
Remaining Life - 6 - 10 Years		1,872
Remaining Life - 11 - 30 Years		17
Remaining Life Over - 30 Years		1,133
Remaining Life - Total Years		28,315
Credit contracts [Member]
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year		50
Remaining Life - 1 - 5 Years		16
Remaining Life - 6 - 10 Years
Remaining Life - 11 - 30 Years
Remaining Life Over - 30 Years
Remaining Life - Total Years		$ 66

[1] As of December 31, 2016, 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 December 31, 2016, the latest maturity date for which we were hedging our exposure to the variability in future cash flows for these instruments was December 2045.