Guarantee Arrangements and Pledged Assets and Collateral - Additional Information (Detail) (USD $)			36 Months Ended																					3 Months Ended		9 Months Ended						3 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Dec. 31, 2007 Hsbc Securities [Member]	Sep. 30, 2014 Securities available-for-sale [Member]	Dec. 31, 2013 Securities available-for-sale [Member]	Sep. 30, 2014 Trading Securities [Member]	Dec. 31, 2013 Trading Securities [Member]	Sep. 30, 2014 Financial standby letters of credit, net of participations [Member]		Dec. 31, 2013 Financial standby letters of credit, net of participations [Member]		Sep. 30, 2014 Performance (non-financial) guarantees [Member]		Dec. 31, 2013 Performance (non-financial) guarantees [Member]		Sep. 30, 2014 Liquidity asset purchase agreements [Member]		Dec. 31, 2013 Liquidity asset purchase agreements [Member]		Sep. 30, 2014 Other liabilities [Member]	Dec. 31, 2013 Other liabilities [Member]	Sep. 30, 2014 Other liabilities [Member] Standby Letters of Credit [Member]	Dec. 31, 2013 Other liabilities [Member] Standby Letters of Credit [Member]	Sep. 30, 2014 Obligation to Repurchase Receivables Sold [Member]	Sep. 30, 2013 Obligation to Repurchase Receivables Sold [Member]	Sep. 30, 2014 Obligation to Repurchase Receivables Sold [Member]	Sep. 30, 2013 Obligation to Repurchase Receivables Sold [Member]	Jun. 30, 2014 Obligation to Repurchase Receivables Sold [Member]	Dec. 31, 2013 Obligation to Repurchase Receivables Sold [Member]	Jun. 30, 2013 Obligation to Repurchase Receivables Sold [Member]	Dec. 31, 2012 Obligation to Repurchase Receivables Sold [Member]	Dec. 31, 2013 Obligation to Repurchase Receivables Sold [Member] Federal National Mortgage Association [Member]	Mar. 31, 2014 Obligation to Repurchase Receivables Sold [Member] Federal Home Loan Mortgage Corporation [Member]
Guarantor Obligations [Line Items]
Deferred fees on standby letters of credit																						$ 41,000,000	$ 46,000,000
Allowance for credit losses on unfunded standby letters of credit																				19,000,000	18,000,000
Settlement of liability																								0	19,000,000	31,000,000	57,000,000					83,000,000	25,000,000
Release of repurchase reserves																																15,000,000	34,000,000
Loss Contingency Accrual																								30,000,000	198,000,000	30,000,000	198,000,000	34,000,000	99,000,000	217,000,000	219,000,000
Range of possible losses in excess of recorded repurchase liability, minimum																								0		0
Range of possible losses in excess of recorded repurchase liability, maximum																								25,000,000		25,000,000
Guarantor Obligations, Maximum Exposure, Undiscounted	182,070,000,000	191,349,000,000						5,612,000,000	[1],[2]	5,237,000,000	[1],[2]	3,037,000,000	[1]	3,172,000,000	[1]	2,354,000,000	[1]	2,560,000,000	[1]
Securities pledged as collateral that can be sold or repledged by the secured party, fair value				5,149,000,000	10,950,000,000	2,086,000,000	1,296,000,000
Collateral accepted under security repurchase agreements but not reported on the balance sheet that can be sold or repledged, fair value	4,895,000,000	4,187,000,000
Collateral accepted under security repurchase agreements that has been sold or repledged under repurchase agreements or to cover short sales	3,597,000,000	2,771,000,000
Whole loan securitization			$ 24,000,000,000

[1] For standby letters of credit and liquidity asset purchase agreements, maximum loss represents losses to be recognized assuming the letter of credit and liquidity facilities have been fully drawn and the obligors have defaulted with zero recovery.

[2] Includes $932 million and $865 million issued for the benefit of HSBC affiliates at September 30, 2014 and December 31, 2013, respectively.