Securities (Available-for-Sale and Held-to-Maturity Securities) (Detail) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Investment Holdings
Available-for-sale securities, fair value	[1]	$ 31,183	$ 29,044
Available-for-sale securities, unrealized losses		(191)	(101)
Available-for-sale securities, unrealized gains		350	467
Available-for-sale and other securities, Amortized Cost		31,024	28,678
Held-to-maturity securities, fair value		26	70
Held-to-maturity, unrealized losses		0	0
Held-to-maturity, unrealized gains		0	0
Held-to-maturity securities, amortized cost	[2]	26	70
U.S. Treasury and federal agencies
Investment Holdings
Available-for-sale securities, fair value		549	1,187
Available-for-sale securities, unrealized losses		0	0
Available-for-sale securities, unrealized gains		2	32
Available-for-sale and other securities, Amortized Cost		547	1,155
Obligations of states and political subdivisions
Investment Holdings
Available-for-sale securities, fair value		45	52
Available-for-sale securities, unrealized losses		0	0
Available-for-sale securities, unrealized gains		1	2
Available-for-sale and other securities, Amortized Cost		44	50
Held-to-maturity securities, fair value		24	68
Held-to-maturity, unrealized losses		0	0
Held-to-maturity, unrealized gains		0	0
Held-to-maturity securities, amortized cost		24	68
Agency mortgage-backed securities | Residential mortgage backed securities
Investment Holdings
Available-for-sale securities, fair value	[3]	15,608	15,081
Available-for-sale securities, unrealized losses	[3]	(95)	(13)
Available-for-sale securities, unrealized gains	[3]	178	283
Available-for-sale and other securities, Amortized Cost	[3]	15,525	14,811
Agency mortgage-backed securities | Commercial mortgage-backed securities
Investment Holdings
Available-for-sale securities, fair value		9,055	7,862
Available-for-sale securities, unrealized losses		(61)	(33)
Available-for-sale securities, unrealized gains		87	100
Available-for-sale and other securities, Amortized Cost		9,029	7,795
Non-agency mortgage-backed securities | Commercial mortgage-backed securities
Investment Holdings
Available-for-sale securities, fair value		3,112	2,804
Available-for-sale securities, unrealized losses		(15)	(32)
Available-for-sale securities, unrealized gains		51	35
Available-for-sale and other securities, Amortized Cost		3,076	2,801
Asset-backed securities and other debt securities
Investment Holdings
Available-for-sale securities, fair value		2,116	1,355
Available-for-sale securities, unrealized losses		(18)	(21)
Available-for-sale securities, unrealized gains		28	13
Available-for-sale and other securities, Amortized Cost		2,106	1,363
Held-to-maturity securities, fair value		2	2
Held-to-maturity, unrealized losses		0	0
Held-to-maturity, unrealized gains		0	0
Held-to-maturity securities, amortized cost		2	2
Equity securities
Investment Holdings
Available-for-sale securities, fair value	[4]	698	703
Available-for-sale securities, unrealized losses	[4]	(2)	(2)
Available-for-sale securities, unrealized gains	[4]	3	2
Available-for-sale and other securities, Amortized Cost	[4]	$ 697	$ 703

[1] Amortized cost of $ 31,024 and $ 28,678 at December 31, 2016 and 2015 , respectively.

[2] Fair value of $ 26 and $ 70 at December 31, 2016 and 2015 , respectively.

[3] Includes interest-only mortgage-backed securities of $ 60 and $ 50 as of December 31, 2016 and 2015 , respectively, recorded at fair value with fair value changes recorded in securities gains, net , i n the Consolidated Statements of Income .

[4] Equity securities consist of FHLB, FRB and DTCC restricted stock holdings of $ 248 , $ 358 , and $ 1 , respectively, at December 31, 2016 and $ 248 , $ 355 and $ 1 , respectively, at December 31, 2015 , that are carried at cost, and certain mutual fund and equity security holdings.