Derivative Instruments (Maturity Of The Notional Amounts Of Derivative Financial Instruments) (Details) $ in Millions	Mar. 31, 2020 USD ($)
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year	$ 46,057
Remaining Life - 1 - 5 Years	62,638
Remaining Life - 6 - 10 Years	30,552
Remaining Life - 11 - 30 Years	34,188
Remaining Life Over - 30 Years	6,954
Remaining Life - Total Years	180,389
Interest rate contracts [Member]
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year	15,089
Remaining Life - 1 - 5 Years	48,226
Remaining Life - 6 - 10 Years	24,802
Remaining Life - 11 - 30 Years	32,669
Remaining Life Over - 30 Years	618
Remaining Life - Total Years	121,404
Foreign currency contracts [Member]
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year	146
Remaining Life - 1 - 5 Years	370
Remaining Life - 6 - 10 Years	1,013
Remaining Life - 11 - 30 Years	1,507
Remaining Life Over - 30 Years	42
Remaining Life - Total Years	3,078
Equity market contracts [Member]
Maturity of the notional amounts of derivative financial instruments
Remaining Life Less Than 1 Year	30,822
Remaining Life - 1 - 5 Years	14,042
Remaining Life - 6 - 10 Years	4,343
Remaining Life - 11 - 30 Years	12
Remaining Life Over - 30 Years	6,294
Remaining Life - Total Years	55,513
Credit contracts [Member]
Maturity of the notional amounts of derivative financial instruments
Remaining Life - 6 - 10 Years	394
Remaining Life - Total Years	$ 394