Investment Securities (Summary Of Investment Securities Available-For-Sale) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Investment securities available-for-sale, Amortized Cost	[1]	$ 11,061	$ 10,829
Investment securities available-for-sale, Gross Unrealized Gains	[1]	23	57
Investment securities available-for-sale, Gross Unrealized Losses	[1]	146	99
Investment securities available-for-sale, Fair Value	[1]	10,938	10,787
Investment securities held-to-maturity, Amortized Cost		1,266	1,582
Investment securities held-to-maturity, Fair Value		1,246
Unrealized losses on available-for-sale securities transferred to held-to-maturity		9	12
U.S. Treasury and other U.S. government agency securities
Investment securities available-for-sale, Amortized Cost		2,743	2,772
Investment securities available-for-sale, Gross Unrealized Gains		0	8
Investment securities available-for-sale, Gross Unrealized Losses		16	1
Investment securities available-for-sale, Fair Value		2,727	2,779
Residential mortgage-backed securities
Investment securities available-for-sale, Amortized Cost	[2]	8,230	7,921
Investment securities available-for-sale, Gross Unrealized Gains	[2]	22	48
Investment securities available-for-sale, Gross Unrealized Losses	[2]	128	97
Investment securities available-for-sale, Fair Value	[2]	8,124	7,872
Investment securities held-to-maturity, Amortized Cost	[2],[3]	1,266	1,582
Investment securities held-to-maturity, Gross Unrealized Gains	[2],[3]	0	1
Investment securities held-to-maturity, Gross Unrealized Losses	[2],[3]	20	7
Investment securities held-to-maturity, Fair Value	[2],[3]	1,246	1,576
State and municipal securities
Investment securities available-for-sale, Amortized Cost		5	7
Investment securities available-for-sale, Gross Unrealized Gains		0	0
Investment securities available-for-sale, Gross Unrealized Losses		0	0
Investment securities available-for-sale, Fair Value		5	7
Equity and other non-debt securities
Investment securities available-for-sale, Amortized Cost		83	129
Investment securities available-for-sale, Gross Unrealized Gains		1	1
Investment securities available-for-sale, Gross Unrealized Losses		2	1
Investment securities available-for-sale, Fair Value		82	129
Investment securities held-to-maturity, Amortized Cost		0
Investment securities held-to-maturity, Fair Value		0
Auction-rate securities
Investment securities available-for-sale, Amortized Cost		51	55
Investment securities available-for-sale, Fair Value		$ 49	$ 54

[1] Included auction-rate securities at amortized cost and fair value of $51 million and $49 million, respectively, as of December 31, 2017 and $55 million and $54 million, respectively, as of December 31, 2016.

[2] Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.

[3] The amortized cost of investment securities held-to-maturity included the unamortized balance of net unrealized losses as of the transfer date of $9 million and $12 million at December 31, 2017 and 2016, respectively, related to securities transferred from available-for-sale, which is included in accumulated other comprehensive loss.