Long-Term Debt-Additional Information (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 capital_funding_trust	Dec. 31, 2013
Junior subordinated debt [Member]
Debt Instrument [Line Items]
Number of capital funding trusts holding long-term debt	3
Structured Notes [Member]
Debt Instrument [Line Items]
Long-term debt carried at fair value	6,612,000,000	$ 5,693,000,000
Subordinated Debt [Member]
Debt Instrument [Line Items]
Long-term debt carried at fair value	2,179,000,000	1,893,000,000
HSBC Bank USA and its Subsidiaries [Member]
Debt Instrument [Line Items]
Long-term debt due from subsidiaries	900,000,000	900,000,000
Federal Home Loan Bank of New York [Member] | Long-term Debt [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Long-term Line of Credit	1,000,000,000	1,000,000,000
Current borrowing capacity	16,017,000,000