Financial Statements of HSBC USA Inc. (Parent) Statement of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Condensed Financial Statements, Captions [Line Items]
Net income	$ 393	$ 548	$ 688
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	22	13	22
Net change in other assets and liabilities	1,359	(1,044)	172
Net cash provided by operating activities	2,425	1,936	1,820
Cash flows from investing activities
Sales and maturities of securities	0	0	1
Other, net	(140)	(17)	103
Net cash provided by (used in) investing activities	3,937	(18,296)	35,072
Cash flows from financing activities
Net change in deposits from other HSBC affiliates	(1,941)	(12,534)	(2,107)
Net change in short-term borrowings	3,969	(393)	1,386
Issuance of long-term debt	4,553	5,931	7,711
Repayment of long-term debt	(4,448)	(3,229)	(10,044)
Preferred stock redemption	0	(1,000)	0
Return of capital to parent	0	(2,000)	(1,000)
Other decreases in capital surplus	(8)	(2)	(4)
Net cash provided by (used in) financing activities	609	(13,304)	(4,135)
Net change in cash and due from banks and interest bearing deposits with banks	6,971	(29,664)	32,757
Cash and due from banks and interest bearing deposits with banks at beginning of period	18,748	48,412	15,655
Cash and due from banks and interest bearing deposits with banks at end of period	25,719	18,748	48,412
Cash paid for:
Interest	5,123	1,660	606
HSBC USA
Condensed Financial Statements, Captions [Line Items]
Net income	393	548	688
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	3	1	1
Net change in other assets and liabilities	794	(2,073)	(313)
Undistributed loss (gain) of subsidiaries	1,083	(669)	(702)
Other, net	(9)	2	(4)
Net cash provided by operating activities	2,264	(2,191)	(330)
Cash flows from investing activities
Net change in investments in and balances due from subsidiaries	(889)	2,291	2,713
Net change in receivables from other HSBC affiliates	875	(888)	(1,345)
Other, net	0	14	0
Net cash provided by (used in) investing activities	(14)	1,417	1,369
Cash flows from financing activities
Net change in deposits from other HSBC affiliates	41	(17)	13
Net change in short-term borrowings	(878)	1,135	(815)
Issuance of long-term debt	4,546	5,824	6,844
Repayment of long-term debt	(4,435)	(3,089)	(6,000)
Preferred stock redemption	0	(1,000)	0
Return of capital to parent	0	(2,000)	(1,000)
Other decreases in capital surplus	(8)	(2)	(4)
Dividends paid	(1,516)	(77)	(77)
Net cash provided by (used in) financing activities	(2,250)	774	(1,039)
Net change in cash and due from banks and interest bearing deposits with banks	0	0	0
Cash and due from banks and interest bearing deposits with banks at beginning of period	0	0	0
Cash and due from banks and interest bearing deposits with banks at end of period	0	0	0
Cash paid for:
Interest	$ 1,178	$ 373	$ 167