Investment Securities (Schedule Of Realized Gain (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Investments, Debt and Equity Securities [Abstract]
Available-for-sale securities, gross realized gains	$ 6	$ 19	$ 38	$ 124
Net realized gains on available-for-sale securities	6	19	38	124
Net realized gain on equity securities	40	80	114	81
Net unrealized gain (loss) on equity securities	19	89	36	(96)
Other gain on investments, net	$ 65	$ 188	$ 188	$ 109