Regulation and Capital Adequacy - Consolidated Regulatory Capital Ratios (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Regulation And Capital Adequacy [Abstract]
Common shareholders' equity	$ 71,899	$ 71,267
Deductions for goodwill and identifiable intangible assets, net of deferred tax liabilities	(2,953)
Deductions for investments in nonconsolidated financial institutions	(1,818)
Other adjustments	287
Common Equity Tier 1	67,415	63,248
Perpetual non-cumulative preferred stock	7,200	7,200
Junior subordinated debt issued to trusts	1,375	2,063
Deduction for goodwill and identifiable intangible assets		(4,376)
Deduction for equity investments in certain entities		(3,314)
Other adjustments	(582)	(369)
Tier 1 Capital	75,408	72,471	66,977
Qualifying subordinated debt	12,321	12,773
Junior subordinated debt issued to trusts	1,375	687
Other adjustments	197	172
Tier 2 Capital	13,893	13,632	13,429
Total Capital	89,301	86,103
Credit RWAs	308,102	268,247
Market RWAs	154,221	164,979
Total RWAs	$ 462,323	$ 433,226	$ 399,928
CET1 Ratio	14.60%
Tier 1 capital ratio	16.30%	16.70%
Total Capital Ratio	19.30%	19.90%
Tier 1 leverage ratio	8.20%	8.10%