Fair Value and Gross Unrealized Losses on Available-for-Sale Securities (Detail) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value		$ 8,248	$ 714
Less than 12 months Unrealized Losses		(90)	(3)
12 months or more Fair Value		263	104
12 months or more Unrealized Losses		(11)	(2)
Total Fair Value		8,511	818
Total Unrealized Losses		(101)	(5)
Agency mortgage-backed securities | Residential mortgage backed securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value		2,903	73
Less than 12 months Unrealized Losses		(13)	(1)
Total Fair Value		2,903	73
Total Unrealized Losses	[1]	(13)	(1)
Agency mortgage-backed securities | Commercial mortgage backed securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value		3,111	355
Less than 12 months Unrealized Losses		(33)	(1)
Total Fair Value		3,111	355
Total Unrealized Losses		(33)	(1)
Non-agency mortgage-backed securities | Commercial mortgage backed securities
Investments, Unrealized Loss Position [Line Items]
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 [Line Items]
Less than 12 months Fair Value		623	286
Less than 12 months Unrealized Losses		(11)	(1)
12 months or more Fair Value		226	74
12 months or more Unrealized Losses		(10)	(1)
Total Fair Value		849	360
Total Unrealized Losses		(21)	(2)
Equity securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value		1
Less than 12 months Unrealized Losses		(1)
12 months or more Fair Value		37	30
12 months or more Unrealized Losses		(1)	(1)
Total Fair Value		38	30
Total Unrealized Losses	[2]	$ (2)	$ (1)

[1] 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.

[2] 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.