Investment Securities (Schedule Of Realized Gain (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Available-for-sale securities, gross realized gains	$ 19	$ 24	$ 124	$ 34
Available-for-sale securities, gross realized losses	0	0	0	(1)
Net realized gains on available-for-sale securities	19	24	124	33
Net realized gain on equity securities	80	10	81	39
Net unrealized gain (loss) on equity securities	89	5	(96)	75
Other gain on investments, net	$ 188	$ 39	$ 109	$ 147