Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Loss (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Equity [Abstract]
Unrealized net gains on hedges arising during the period, Before Tax Amount			$ 9	$ 38
Less: Reclassification adjustment for net losses on hedges included in interest income for loans and interest expense on long-term debt, Before Tax Amount			(14)	(5)
Net change in unrealized gains (losses) on hedges, Before Tax Amount			(5)	33
Unrealized holding gains arising during the period on securities available for sale, Before Tax Amount			(503)	147
Reclassification adjustment for net gains on securities available for sale included in securities gains, net income, Before Tax Amount			(123)	(47)
Less: accretion of fair value adjustment on securities available for sale, Before Tax Amount			(38)	(1)
Less: accretion of fair value adjustment on held to maturity securities, Before Tax Amount			(11)	(14)
Less: amortization of net unrealized losses on held to maturity securities, Before Tax Amount			25	56
Net change in unrealized gains (losses) on securities, Before Tax Amount			(650)	141
Foreign currency translation adjustment, Before Tax Amount			(5)	(1)
Recognized net actuarial loss, Before Tax Amount			58	49
Net change in pension and other benefits, Before Tax Amount			58	49
Net change in accumulated other comprehensive loss, Before Tax Amount			(602)	222
Unrealized net gains on hedges arising during the period, Tax Effect			(3)	(15)
Less: Reclassification adjustment for net losses on hedges included in interest income for loans and interest expense on long-term debt, Tax Effect			5	2
Net change in unrealized gains (losses) on hedges, Tax Effect			2	(13)
Unrealized holding gains arising during the period on securities available for sale, Tax Effect			197	(58)
Reclassification adjustment for net gains on securities available for sale included in net income, Tax Effect			49	18
Less: accretion of fair value adjustment on securities available for sale, Tax Effect			16	1
Less: accretion of fair value adjustment on held to maturity securities, Tax Effect			4	6
Less: amortization of net unrealized losses on held to maturity securities, Tax Effect			(10)	(22)
Net change in unrealized gains on securities, Tax Effect			256	(55)
Foreign currency translation adjustment, Tax Effect			2	1
Recognized net actuarial loss, Tax Effect			(23)	(19)
Net change in pension and other benefits, Tax Effect			(23)	(19)
Net change in accumulated other comprehensive loss, Tax Effect			237	(86)
Unrealized net gains on hedges arising during the period, Net of Tax			6	23
Less: Reclassification adjustment for net losses on hedges included in interest income for loans and interest expense on long-term debt, Net of Tax			(9)	(3)
Net change in unrealized gains (losses) on hedges, Net of Tax	(3)	15	(3)	20
Unrealized holding gains arising during the period on securities available for sale, Net of Tax			(306)	89
Reclassification adjustment for net gains on securities available for sale included in net income, Net of Tax			(74)	(29)
Less: accretion of fair value adjustment on securities available for sale, Net of Tax			(22)
Less: accretion of fair value adjustment on held to maturity securities, Net of Tax			(7)	(8)
Less: amortization of net unrealized losses on held to maturity securities, Net of Tax			15	34
Net change in unrealized gains on securities, Net of Tax	(330)	47	(394)	86
Foreign currency translation adjustment, Net of Tax	(2)	(1)	(3)
Recognized net actuarial loss, Net of Tax			35	30
Net change in pension and other benefits, Net of Tax	17	14	35	30
Net change in accumulated other comprehensive loss, Net of Tax	$ (318)	$ 75	$ (365)	$ 136