Securities (Fair Value and Gross Unrealized Losses on Available-for-Sale Securities) (Detail) - USD ($) $ in Millions	Mar. 31, 2017		Dec. 31, 2016
Investments, Unrealized Loss Position
Less than 12 months Fair Value	$ 9,781		$ 11,079
Less than 12 months Unrealized Losses	(167)		(172)
12 months or more Fair Value	562		545
12 months or more Unrealized Losses	(21)		(19)
Total Fair Value	10,343		11,624
Total Unrealized Losses	(188)		(191)
U.S. Treasury and federal agencies
Investments, Unrealized Loss Position
Less than 12 months Fair Value	101		199
Less than 12 months Unrealized Losses	0		0
12 months or more Fair Value	0		0
12 months or more Unrealized Losses	0		0
Total Fair Value	101		199
Total Unrealized Losses	0		0
Agency mortgage-backed securities | Residential mortgage backed securities
Investments, Unrealized Loss Position
Less than 12 months Fair Value	5,144		6,223
Less than 12 months Unrealized Losses	(82)		(88)
12 months or more Fair Value	161		172
12 months or more Unrealized Losses	(8)		(7)
Total Fair Value	5,305		6,395
Total Unrealized Losses	(90)	[1]	(95)	[2]
Agency mortgage-backed securities | Commercial mortgage backed securities
Investments, Unrealized Loss Position
Less than 12 months Fair Value	2,931		3,183
Less than 12 months Unrealized Losses	(63)		(61)
12 months or more Fair Value	0		0
12 months or more Unrealized Losses	0		0
Total Fair Value	2,931		3,183
Total Unrealized Losses	(63)		(61)
Non-agency mortgage-backed securities | Commercial mortgage backed securities
Investments, Unrealized Loss Position
Less than 12 months Fair Value	1,283		1,052
Less than 12 months Unrealized Losses	(16)		(15)
12 months or more Fair Value	0		0
12 months or more Unrealized Losses	0		0
Total Fair Value	1,283		1,052
Total Unrealized Losses	(16)		(15)
Asset-backed securities and other debt securities
Investments, Unrealized Loss Position
Less than 12 months Fair Value	322		422
Less than 12 months Unrealized Losses	(6)		(8)
12 months or more Fair Value	364		336
12 months or more Unrealized Losses	(11)		(10)
Total Fair Value	686		758
Total Unrealized Losses	(17)		(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	(2)		(2)
Total Fair Value	37		37
Total Unrealized Losses	$ (2)	[3]	$ (2)	[4]

[1] Includes interest-only mortgage- backed securities of $ 42 as of March 31, 2017 , recorded at fair value with fair value changes re corded in securities gains, net , in the Condensed Consolidated Statement s 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 , $ 359 and $ 1 , respectively , at March 31, 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