Investment Securities (Summary Of Investment Securities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Investment [Line Items]
Held-to-maturity, fair value	$ 597
Available-for-sale debt securities, Amortized cost	13,686
Available-for-sale debt securities, Estimated fair value	13,725
Available-for-sale, at fair value	13,725	$ 14,737
Available-for-sale Securities, Amortized Cost Basis	13,686	15,040
Available-for-sale, Gross unrealized gains, Recognized in OCI	126	23
Available-for-sale, Gross unrealized losses, Recognized in OCI	87	326
amortized cost of investment securities	14,278	15,814
Gross Unrealized Gains of Investment Securities Recognized in OCI	131	27
Gross Unrealized Losses of Investment Securities Recognized in OCI	87	337
Estimated Fair Value of Investment Securities	14,322	15,504
US Treasury Securities [Member]
Investment [Line Items]
Available-for-sale debt securities, Amortized cost	25	40
Available-for-sale debt securities, Gross unrealized gains, Recognized in OCI	0	0
Available-for-sale debt securities, Gross unrealized losses, Recognized in OCI	0	0
Available-for-sale debt securities, Estimated fair value	25	40
Agency Securities [Member]
Investment [Line Items]
Available-for-sale debt securities, Amortized cost	1,301	1,394
Available-for-sale debt securities, Gross unrealized gains, Recognized in OCI	5	0
Available-for-sale debt securities, Gross unrealized losses, Recognized in OCI	4	19
Available-for-sale debt securities, Estimated fair value	1,302	1,375
Agency Guaranteed Mortgage Backed Securities [Member]
Investment [Line Items]
Available-for-sale debt securities, Amortized cost	9,518	10,236
Available-for-sale debt securities, Gross unrealized gains, Recognized in OCI	83	18
Available-for-sale debt securities, Gross unrealized losses, Recognized in OCI	42	240
Available-for-sale debt securities, Estimated fair value	9,559	10,014
Small Business Administration Loan Backed Securities [Member]
Investment [Line Items]
Available-for-sale debt securities, Amortized cost	1,535	2,042
Available-for-sale debt securities, Gross unrealized gains, Recognized in OCI	1	1
Available-for-sale debt securities, Gross unrealized losses, Recognized in OCI	41	47
Available-for-sale debt securities, Estimated fair value	1,495	1,996
US States and Political Subdivisions Debt Securities [Member]
Investment [Line Items]
Held-to-maturity, Amortized cost	592	774
Held-to-maturity, fair value	597	767
Available-for-sale debt securities, Amortized cost	1,282	1,303
Available-for-sale debt securities, Gross unrealized gains, Recognized in OCI	37	4
Available-for-sale debt securities, Gross unrealized losses, Recognized in OCI	0	16
Available-for-sale debt securities, Estimated fair value	1,319	1,291
Deb Securities, Held-to-maturity, Gross Unrealized Gains	5	4
Debt Securities, Held-to-maturity, Gross Unrealized Losses	0	11
Available-for-sale, Other debt securities [Member]
Investment [Line Items]
Available-for-sale debt securities, Amortized cost	25	25
Available-for-sale debt securities, Gross unrealized gains, Recognized in OCI	0	0
Available-for-sale debt securities, Gross unrealized losses, Recognized in OCI	0	4
Available-for-sale debt securities, Estimated fair value	$ 25	$ 21