Available-for-Sale and Held-to-Maturity Securities (Detail) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Investment Holdings [Line Items]
Available-for-sale and other securities, fair value	[1]	$ 29,044	$ 22,408
Available-for-sale and other securities, unrealized losses		(101)	(5)
Available-for-sale and other securities, unrealized gains		467	736
Available-for-sale and other securities, Amortized Cost		28,678	21,677
Held-to-maturity securities, fair value		70	187
Held-to-maturity securities, amortized cost	[2]	70	187
U.S. Treasury and federal agencies
Investment Holdings [Line Items]
Available-for-sale and other securities, fair value		1,187	1,632
Available-for-sale and other securities, unrealized gains		32	87
Available-for-sale and other securities, Amortized Cost		1,155	1,545
Obligations of states and political subdivisions
Investment Holdings [Line Items]
Available-for-sale and other securities, fair value		52	192
Available-for-sale and other securities, unrealized gains		2	7
Available-for-sale and other securities, Amortized Cost		50	185
Held-to-maturity securities, fair value		68	186
Held-to-maturity securities, amortized cost		68	186
Agency mortgage-backed securities | Residential mortgage backed securities
Investment Holdings [Line Items]
Available-for-sale and other securities, fair value	[3]	15,081	12,404
Available-for-sale and other securities, unrealized losses	[3]	(13)	(1)
Available-for-sale and other securities, unrealized gains	[3]	283	437
Available-for-sale and other securities, Amortized Cost	[3]	14,811	11,968
Agency mortgage-backed securities | Commercial mortgage backed securities
Investment Holdings [Line Items]
Available-for-sale and other securities, fair value		7,862	4,565
Available-for-sale and other securities, unrealized losses		(33)	(1)
Available-for-sale and other securities, unrealized gains		100	101
Available-for-sale and other securities, Amortized Cost		7,795	4,465
Non-agency mortgage-backed securities | Commercial mortgage backed securities
Investment Holdings [Line Items]
Available-for-sale and other securities, fair value		2,804	1,550
Available-for-sale and other securities, unrealized losses		(32)
Available-for-sale and other securities, unrealized gains		35	61
Available-for-sale and other securities, Amortized Cost		2,801	1,489
Asset-backed securities and other debt securities
Investment Holdings [Line Items]
Available-for-sale and other securities, fair value		1,355	1,362
Available-for-sale and other securities, unrealized losses		(21)	(2)
Available-for-sale and other securities, unrealized gains		13	40
Available-for-sale and other securities, Amortized Cost		1,363	1,324
Held-to-maturity securities, fair value		2	1
Held-to-maturity securities, amortized cost		2	1
Equity securities
Investment Holdings [Line Items]
Available-for-sale and other securities, fair value	[4]	703	703
Available-for-sale and other securities, unrealized losses	[4]	(2)	(1)
Available-for-sale and other securities, unrealized gains	[4]	2	3
Available-for-sale and other securities, Amortized Cost	[4]	$ 703	$ 701

[1] Amortized cost of $28,678 and $21,677 at December 31, 2015 and 2014, respectively.

[2] Fair value of $70 and $187 at December 31, 2015 and 2014, respectively.

[3] Includes interest-only mortgage-backed securities of $50 and $175 as of December 31, 2015 and 2014, respectively, recorded at fair value with fair value changes recorded in securities gains, net, in the Consolidated Statements of Income.

[4] Equity securities consist of FHLB, FRB and DTCC restricted stock holdings of $248, $355, and $1, respectively, at December 31, 2015 and $248, $352 and $0, respectively, at December 31, 2014, that are carried at cost, and certain mutual fund and equity security holdings.