Guarantee Arrangements and Pledged Assets and Collateral - Additional Information (Detail) (USD $)	12 Months Ended				36 Months Ended						3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2007 HSBC Securities [Member]	Dec. 31, 2013 Available-for-sale Securities [Member]	Dec. 31, 2012 Available-for-sale Securities [Member]	Dec. 31, 2013 Trading Assets [Member]	Dec. 31, 2012 Trading Assets [Member]	Dec. 31, 2013 Financial Guarantee [Member] Collateralized Securities [Member]	Dec. 31, 2013 Federal National Mortgage Association [Member]
Guarantor Obligations [Line Items]
Outstanding financial standby letters of credit	$ 5,200,000,000	$ 5,600,000,000
Outstanding financial standby performance guarantees	3,200,000,000	2,900,000,000
Deferred fee on stand by letters of credit	46,000,000	46,000,000
Allowance for credit losses on unfunded standby letters of credit	18,000,000	19,000,000
Minimum time to resolve case	3 months
Maximum time to resolve case	12 months
Principal amount outstanding on loans sold to government sponsored entities	11,900,000,000	15,100,000,000
Principal amount outstanding on loans from our legacy broker channel	7,600,000,000	9,600,000,000
Repurchase demands received from our legacy broker channel	245,000,000	393,000,000	300,000,000
Outstanding repurchase demands on loans sourced from our legacy broker channel	26,000,000	65,000,000	87,000,000
Settlement with FNMA											83,000,000
Release of provision											15,000,000
Repurchase liability for loans	99,000,000	219,000,000	237,000,000	262,000,000
Range of possible losses in excess of recorded repurchase liability, minimum										0
Range of possible losses in excess of recorded repurchase liability, maximum										90,000,000
Liquidity facilities	2,100,000,000	2,200,000,000
Securities available-for-sale						10,900,000,000	6,500,000,000
Fair value of collateral received								1,300,000,000	2,200,000,000
Separately reported available-for-sale pledged assets	4,200,000,000	5,700,000,000
Securities sold under agreements to repurchase	2,700,000,000	1,300,000,000
Net rental expense	149,000,000	147,000,000	148,000,000
Whole loan securitization					$ 24,000,000,000