Securities - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended									3 Months Ended		9 Months Ended
	Mar. 31, 2013 security	Sep. 30, 2014 security	Sep. 30, 2013	Dec. 31, 2013 security	Sep. 30, 2014 Asset backed securities [Member]	Dec. 31, 2013 Asset backed securities [Member]	Sep. 30, 2014 Asset backed securities issued by consolidated VIE [Member]		Dec. 31, 2013 Asset backed securities issued by consolidated VIE [Member]		Sep. 30, 2014 Held-to-maturity Securities [Member] security	Sep. 30, 2013 Held-to-maturity Securities [Member]	Sep. 30, 2014 Held-to-maturity Securities [Member] security	Sep. 30, 2013 Held-to-maturity Securities [Member]	Sep. 30, 2014 Other assets [Member]	Dec. 31, 2013 Other assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities held-to-maturity		$ 12,045,000,000		$ 1,358,000,000	$ 76,000,000	$ 200,000,000
Asset backed securities with changes to other than temporary impairment estimates related to credit component											2		2
Increase in credit losses for which an other-than-temporary impairment was previously recognized											4,000,000	0	11,000,000	0
Non-Credit Loss Component of OTTI Securities, Held-to-Maturity Securities		88,000,000		104,000,000			88,000,000	[1]	104,000,000	[1]
Assets backed securities in available for sale portfolio		17		22
Assets backed securities wrapped by monoline insurance company		5		8
Value of asset backed securities backed by insurance company		187,000,000		321,000,000
Fair value of asset backed securities		248,000,000		448,000,000
Available-for-sale securities, backed by insurance company, accumulated unrecognized holding loss		19,000,000		42,000,000
Fair value of financial guarantee		92,000,000		98,000,000
Number of assets sold from held-to-maturity portfolio	6
Sold security at carrying value	71,000,000
Gain (loss) on held-to-maturity securities	8,000,000	(11,000,000)	8,000,000
Federal Home Loan Bank Stock															108,000,000	139,000,000
Federal Reserve Bank Stock															$ 483,000,000	$ 483,000,000

[1] Relates to securities held by Bryant Park Funding LLC ("Bryant Park"), a variable interest entity which was consolidated in the second quarter of 2013. See Note 16, "Variable Interest Entities" for additional information.