Securities (Fair Value and Gross Unrealized Losses on Available-for-Sale Securities) (Detail) - USD ($) $ in Millions	Jun. 30, 2017		Dec. 31, 2016
Investments, Unrealized Loss Position
Less than 12 months Fair Value	$ 8,347		$ 11,079
Less than 12 months Unrealized Losses	(97)		(172)
12 months or more Fair Value	562		545
12 months or more Unrealized Losses	(24)		(19)
Total Fair Value	8,909		11,624
Total Unrealized Losses	(121)		(191)
U.S. Treasury and federal agencies
Investments, Unrealized Loss Position
Less than 12 months Fair Value			199
Less than 12 months Unrealized Losses			0
12 months or more Fair Value			0
12 months or more Unrealized Losses			0
Total Fair Value			199
Total Unrealized Losses	0		0
Agency mortgage-backed securities | Residential mortgage backed securities
Investments, Unrealized Loss Position
Less than 12 months Fair Value	5,047		6,223
Less than 12 months Unrealized Losses	(48)		(88)
12 months or more Fair Value	152		172
12 months or more Unrealized Losses	(7)		(7)
Total Fair Value	5,199		6,395
Total Unrealized Losses	(55)	[1]	(95)	[2]
Agency mortgage-backed securities | Commercial mortgage backed securities
Investments, Unrealized Loss Position
Less than 12 months Fair Value	2,263		3,183
Less than 12 months Unrealized Losses	(38)		(61)
12 months or more Fair Value	0		0
12 months or more Unrealized Losses	0		0
Total Fair Value	2,263		3,183
Total Unrealized Losses	(38)		(61)
Non-agency mortgage-backed securities | Commercial mortgage backed securities
Investments, Unrealized Loss Position
Less than 12 months Fair Value	710		1,052
Less than 12 months Unrealized Losses	(6)		(15)
12 months or more Fair Value	0		0
12 months or more Unrealized Losses	0		0
Total Fair Value	710		1,052
Total Unrealized Losses	(6)		(15)
Asset-backed securities and other debt securities
Investments, Unrealized Loss Position
Less than 12 months Fair Value	327		422
Less than 12 months Unrealized Losses	(5)		(8)
12 months or more Fair Value	373		336
12 months or more Unrealized Losses	(16)		(10)
Total Fair Value	700		758
Total Unrealized Losses	(21)		(18)
Equity securities
Investments, Unrealized Loss Position
Less than 12 months Fair Value	0		0
Less than 12 months Unrealized Losses	0		0
12 months or more Fair Value	37		37
12 months or more Unrealized Losses	(1)		(2)
Total Fair Value	37		37
Total Unrealized Losses	$ (1)	[3]	$ (2)	[4]

[1] Includes interest-only mortgage-backed securities of $ 39 as of June 30, 2017 , recorded at fair value with fair value changes recorded in securities gains, net, in the Condensed Consolidated Statements of Income.

[2] Includes interest-only mortgage-backed securities of $ 60 as of December 31, 2016 , recorded at fair value with fair value changes recorded in securities gains, net, in the Condensed Consolidated Statements of Income.

[3] Equity securities consist of FHLB, FRB and DTCC restricted stock holdings of $ 248 , $ 360 and $ 2 , respectively, at June 30, 2017 , that are carried at cost, and certain mutual fund and equity security holdings.

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