Financial Statements of HSBC USA Inc. (Parent) Statement of Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income:
Other interest income									$ 59	$ 41	$ 41
Other securities gains, net									48	113	202
Other income									55	84	59
Total income									3,781	3,722	3,705
Expenses:
Other Interest Expense									16	(88)	66
Provision for credit losses	$ 267	$ 47	$ (6)	$ 53	$ 64	$ 23	$ 85	$ 16	361	188	193
Goodwill impairment									0	0	616
Income (loss) before income tax	(180)	315	185	240	100	(28)	(27)	253	560	298	(182)
Income tax benefit	55	(111)	(98)	(76)	(30)	29	206	(149)	(230)	56	(156)
Net income (loss)	$ (125)	$ 204	$ 87	$ 164	$ 70	$ 1	$ 179	$ 104	330	354	(338)
HSBC USA Inc [Member]
Income:
Dividends from banking subsidiaries									104	0	0
Dividends from other subsidiaries									1	1	1
Interest from subsidiaries									97	66	67
Interest from other HSBC affiliates									121	117	95
Other interest income									14	22	22
Other securities gains, net									1	0	0
Other income from subsidiaries									(2)	(1)	276
Other income from other HSBC Affiliates									(79)	395	543
Other income									121	(347)	(799)
Total income									378	253	205
Expenses:
Interest to subsidiaries									23	45	45
Interest to other HSBC Affiliates									28	49	59
Other Interest Expense									375	266	231
Provision for credit losses									0	(3)	0
Goodwill impairment									0	0	510
Other expenses with subsidiaries									0	23	0
Other expenses									6	182	124
Total expenses									432	562	969
Income (loss) before income tax									(54)	(309)	(764)
Income tax benefit									76	107	101
Loss before equity in undistributed income of subsidiaries									22	(202)	(663)
Equity in undistributed income (loss) of subsidiaries									308	556	325
Net income (loss)									$ 330	$ 354	$ (338)