Securities (Fair Value and Gross Unrealized Losses on Available-for-Sale Securities) (Detail) - USD ($) $ in Millions		Jun. 30, 2016		Dec. 31, 2015
Investments, Unrealized Loss Position
Less than 12 months Fair Value		$ 396		$ 8,248
Less than 12 months Unrealized Losses		(5)		(90)
12 months or more Fair Value		295		263
12 months or more Unrealized Losses		(12)		(11)
Total Fair Value		691		8,511
Total Unrealized Losses		(17)		(101)
Agency mortgage-backed securities | Residential mortgage backed securities
Investments, Unrealized Loss Position
Less than 12 months Fair Value				2,903
Less than 12 months Unrealized Losses				(13)
Total Fair Value				2,903
Total Unrealized Losses	[1]			(13)
Agency mortgage-backed securities | Commercial mortgage backed securities
Investments, Unrealized Loss Position
Less than 12 months Fair Value				3,111
Less than 12 months Unrealized Losses				(33)
Total Fair Value				3,111
Total Unrealized Losses				(33)
Non-agency mortgage-backed securities | Commercial mortgage backed securities
Investments, Unrealized Loss Position
Less than 12 months Fair Value				1,610
Less than 12 months Unrealized Losses				(32)
Total Fair Value				1,610
Total Unrealized Losses				(32)
Asset-backed securities and other debt securities
Investments, Unrealized Loss Position
Less than 12 months Fair Value		396		623
Less than 12 months Unrealized Losses		(5)		(11)
12 months or more Fair Value		264		226
12 months or more Unrealized Losses		(11)		(10)
Total Fair Value		660		849
Total Unrealized Losses		(16)		(21)
Equity securities
Investments, Unrealized Loss Position
Less than 12 months Fair Value				1
Less than 12 months Unrealized Losses				(1)
12 months or more Fair Value		31		37
12 months or more Unrealized Losses		(1)		(1)
Total Fair Value		31		38
Total Unrealized Losses		$ (1)	[2]	$ (2)	[3]

[1] 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.

[2] 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.

[3] 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