Fair Value and Gross Unrealized Losses on Available-for-Sale Securities (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	$ 714		$ 7,849
Less than 12 months Unrealized Losses	(3)		(156)
12 months or more Fair Value	104		137
12 months or more Unrealized Losses	(2)		(3)
Total Fair Value	818		7,986
Total Unrealized Losses	(5)		(159)
Agency mortgage-backed securities | Residential mortgage backed securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	73		7,221
Less than 12 months Unrealized Losses	(1)		(150)
12 months or more Fair Value			1
Total Fair Value	73		7,222
Total Unrealized Losses	(1)	[1]	(150)	[1]
Agency mortgage-backed securities | Commercial mortgage backed securities
Investments, Unrealized Loss Position [Line Items]
12 months or more Fair Value	355
12 months or more Unrealized Losses	(1)
Total Fair Value	355
Total Unrealized Losses	(1)
Non-agency mortgage-backed securities | Commercial mortgage backed securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value			168
Less than 12 months Unrealized Losses			(1)
12 months or more Fair Value			28
Total Fair Value			196
Total Unrealized Losses			(1)
Asset-backed securities and other debt securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	286		427
Less than 12 months Unrealized Losses	(1)		(4)
12 months or more Fair Value	74		104
12 months or more Unrealized Losses	(1)		(3)
Total Fair Value	360		531
Total Unrealized Losses	(2)		(7)
Equity securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value			33
Less than 12 months Unrealized Losses			(1)
12 months or more Fair Value	30		4
12 months or more Unrealized Losses	(1)
Total Fair Value	30		37
Total Unrealized Losses	$ (1)	[2]	$ (1)	[2]

[1] Includes interest-only mortgage-backed securities of $175 and $262 as of December 31, 2014 and 2013, respectively, recorded at fair value with fair value changes recorded in securities gains, net and securities gains, net – non-qualifying hedges on mortgage servicing rights in the Consolidated Statements of Income.

[2] Equity securities consist of FHLB and FRB restricted stock holdings of $248 and $352, respectively, at December 31, 2014 and, $402 and $349, respectively, at December 31, 2013, that are carried at cost, and certain mutual fund and equity security holdings.