Financial Statements of HSBC USA Inc. (Parent) Statement of Cash Flows (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ 354	$ (338)	$ (1,045)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	58	59	61
Net change in other assets and liabilities	180	(491)	37
Net change in trading assets and liabilities	5,091	(1,844)	8,900
Net cash provided by (used in) operating activities	5,950	(1,359)	8,367
Cash flows from investing activities
Other, net	34	(16)	(48)
Net cash provided by (used in) investing activities	(7,319)	1,233	(2,748)
Cash flows from financing activities
Net change in short-term borrowings	(6,340)	3,787	(1,076)
Issuance of long-term debt, net of issuance costs	8,067	5,547	7,626
Repayment of long-term debt	(3,686)	(4,370)	(3,445)
Dividends paid	(73)	(73)	(73)
Capital contribution from parent	0	0	312
Additions (reductions) of capital surplus	4	(17)	(3)
Net cash provided by (used in) financing activities	1,299	(272)	(5,876)
Net change in cash and due from banks	(70)	(398)	(257)
Cash and due from banks at beginning of period	961	1,359	1,616
Cash and due from banks at end of period	891	961	1,359
Cash paid for:
Interest	752	921	1,085
HSBC USA Inc [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	354	(338)	(1,045)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	4	(2)	3
Net change in other assets and liabilities	(1,224)	95	(2,438)
Undistributed loss (gain) of subsidiaries	(556)	(325)	951
Net change in trading assets and liabilities	624	362	(321)
Other, net	(36)	(16)	58
Net cash provided by (used in) operating activities	(834)	(224)	(2,792)
Cash flows from investing activities
Purchases of securities	0	(139)	(342)
Sales and maturities of securities	21	208	14
Net change in loans	26	5	5
Net change in investments in and receivables due from subsidiaries	(6,003)	365	(1,659)
Other, net	0	0	1
Net cash provided by (used in) investing activities	(5,956)	439	(1,981)
Cash flows from financing activities
Net change in short-term borrowings	1,393	(1,643)	186
Issuance of long-term debt, net of issuance costs	8,013	4,401	7,209
Repayment of long-term debt	(2,554)	(2,875)	(2,858)
Dividends paid	(73)	(73)	(73)
Capital contribution from parent	0	0	312
Additions (reductions) of capital surplus	4	(17)	(3)
Net cash provided by (used in) financing activities	6,783	(207)	4,773
Net change in cash and due from banks	(7)	8	0
Cash and due from banks at beginning of period	8	0	0
Cash and due from banks at end of period	1	8	0
Cash paid for:
Interest	$ 363	$ 321	$ 317