Litigation and Regulatory Matters - Additional Information (Detail) (USD $)	0 Months Ended
	Oct. 17, 2013	Mar. 31, 2014
Securities Litigation [Member]
Loss Contingencies [Line Items]
Litigation judgment claims	$ 2,500,000,000
Claims still open to special court	527,000,000
Possible future expenses related to amount of damages		3,500,000,000
Cards Litigation [Member]
Loss Contingencies [Line Items]
Number of opt-out suits filed		35
Number of opt-out suits naming HSBC entities as defendants		1
Lopez v. HSBC USA, N.A., et.al. [Member]
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss		$ 32,000,000