Investment Securities (Contractual Maturity Distribution Of Debt Securities) (Details) - USD ($) $ in Millions		Jun. 30, 2017	Dec. 31, 2016
Available-for-sale, Within one year, Amortized Cost		$ 20
Available-for-sale, After one year through five years, Amortized Cost		2,991
Available-for-sale, After five years through ten years, Amortized Cost		1,833
Available-for-sale, After ten years, Amortized Cost		6,012
Available-for-sale, Subtotal, Amortized Cost		10,856
Available-for-sale, Within one year, Fair Value		20
Available-for-sale, After one year through five years, Fair Value		3,002
Available-for-sale, After five years through ten years, Fair Value		1,861
Available-for-sale, After ten years, Fair Value		5,952
Available-for-sale, Subtotal, Fair Value		10,835
Investment securities available-for-sale, Amortized Cost	[1]	10,965	$ 10,829
Investment securities available-for-sale, Fair Value	[1]	10,944	10,787
Held-to-maturity, Within one year, Amortized Cost		0
Held-to-maturity, After one year through five years, Amortized Cost		0
Held-to-maturity, After five years through ten years, Amortized Cost		21
Held-to-maturities, After ten years, Amortized Cost		1,409
Held-to-maturity Securities		1,430	1,582
Held-to-maturity, Within one year, Fair Value		0
Held-to-maturity Securities, After one year through five years, Fair Value		0
Held-to-maturity Securities, After five years through ten years, Fair Value		20
Held-to-maturity Securities, After ten years, Fair Value		1,404
Held-to-maturity Securities, Fair Value		1,424
Equity and other non-debt securities
Investment securities available-for-sale, Amortized Cost		109	129
Investment securities available-for-sale, Fair Value		$ 109	$ 129

[1] Included auction-rate securities at amortized cost and fair value of $52 million and $51 million, respectively as of June 30, 2017 and $55 million and $54 million, respectively, as of December 31, 2016.