Securities (Available-for-Sale and Held-to-Maturity Securities) (Detail) - USD ($) $ in Millions		Jun. 30, 2016		Dec. 31, 2015
Investment Holdings
Available-for-sale securities, fair value	[1]	$ 31,455		$ 29,044
Available-for-sale securities, unrealized losses		(17)		(101)
Available-for-sale securities, unrealized gains		1,371		467
Available-for-sale and other securities, Amortized Cost		30,101		28,678
Held-to-maturity securities, fair value		62		70
Held-to-maturity securities, amortized cost	[2]	62		70
U.S. Treasury and federal agencies
Investment Holdings
Available-for-sale securities, fair value		1,155		1,187
Available-for-sale securities, unrealized gains		22		32
Available-for-sale and other securities, Amortized Cost		1,133		1,155
Obligations of states and political subdivisions
Investment Holdings
Available-for-sale securities, fair value		52		52
Available-for-sale securities, unrealized gains		3		2
Available-for-sale and other securities, Amortized Cost		49		50
Held-to-maturity securities, fair value		60		68
Held-to-maturity securities, amortized cost		60		68
Agency mortgage-backed securities | Residential mortgage backed securities
Investment Holdings
Available-for-sale securities, fair value		15,694	[3]	15,081	[4]
Available-for-sale securities, unrealized losses	[4]			(13)
Available-for-sale securities, unrealized gains		612	[3]	283	[4]
Available-for-sale and other securities, Amortized Cost		15,082	[3]	14,811	[4]
Agency mortgage-backed securities | Commercial mortgage backed securities
Investment Holdings
Available-for-sale securities, fair value		8,926		7,862
Available-for-sale securities, unrealized losses				(33)
Available-for-sale securities, unrealized gains		537		100
Available-for-sale and other securities, Amortized Cost		8,389		7,795
Non-agency mortgage-backed securities | Commercial mortgage backed securities
Investment Holdings
Available-for-sale securities, fair value		3,079		2,804
Available-for-sale securities, unrealized losses				(32)
Available-for-sale securities, unrealized gains		168		35
Available-for-sale and other securities, Amortized Cost		2,911		2,801
Asset-backed securities and other debt securities
Investment Holdings
Available-for-sale securities, fair value		1,849		1,355
Available-for-sale securities, unrealized losses		(16)		(21)
Available-for-sale securities, unrealized gains		26		13
Available-for-sale and other securities, Amortized Cost		1,839		1,363
Held-to-maturity securities, fair value		2		2
Held-to-maturity securities, amortized cost		2		2
Equity securities
Investment Holdings
Available-for-sale securities, fair value		700	[5]	703	[6]
Available-for-sale securities, unrealized losses		(1)	[5]	(2)	[6]
Available-for-sale securities, unrealized gains		3	[5]	2	[6]
Available-for-sale and other securities, Amortized Cost		$ 698	[5]	$ 703	[6]

[1] Amortized cost of $ 30,101 and $ 28,678 at June 30, 2016 and Dec ember 31, 2015 , respectively.

[2] Fair value of $ 62 and $ 70 at June 30, 2016 and December 31, 2015 , respectively.

[3] Includes interest-only mortgage- backed securities of $ 36 as of June 30, 2016 recorded at fair value with fair value changes re corded in securities gains, net , in the Condensed Consolidated Statement s of Income.

[4] Includes interest-only mortgage- backed securities of $ 50 as of December 31, 2015 , recorded at fair value with fair value changes re corded in securities gains, net , in the Condensed Consolidated Statement s of Income.

[5] Equity securities consist of FHLB, FRB and DTCC restricted stock holdings of $ 248 , $ 356 and $ 1 , respectively , at June 30, 2016 , that are carried at cost, and certain mutual fund and equity security holdings.

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