Retained Earnings and Regulatory Capital Requirements - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Preferred stock, par value (usd per share)		$ 0
Payments for repurchase of redeemable preferred stock		$ 1,265	$ 300	$ 0
Repayments of long-term debt		4,869	9,937	3,686
Capital contribution from parent		$ 0	4,000	0
6.50% Non-Cumulative Series H Preferred Stock [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
HSBC USA preferred stock dividend rate (percent)	6.50%	0.00%
Preferred stock, par value (usd per share)	$ 1,000
Floating Rate Non-Cumulative Series F Preferred Stock [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
HSBC USA preferred stock dividend rate (percent)		0.00%
Preferred stock, par value (usd per share)	25
Floating Rate Non-Cumulative Series G Preferred Stock [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
HSBC USA preferred stock dividend rate (percent)		0.00%
Preferred stock, par value (usd per share)	$ 1,000
6.0% Non-Cumulative Preferred Stock, Series I ($1,000,000 stated value)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
HSBC USA preferred stock dividend rate (percent)		6.00%
HSBC USA Inc [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Payments for repurchase of redeemable preferred stock		$ 1,265	300	0
Repayments of long-term debt		3,815	9,870	2,554
Capital contribution from parent		0	4,000	0
HSBC USA Inc [Member] | Senior debt [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Repayments of long-term debt			4,000
HSBC Bank USA, National Association [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Required reserves with the Federal Reserve Bank		3,139	$ 2,188
HSBC Bank USA, National Association [Member] | Noncumulative Preferred Stock [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
HSBC USA preferred stock issued (shares)			250
Capital distribution to subsidiary			$ 2,500
HSBC Bank USA, National Association [Member] | Subordinated Debt [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Repayments of long-term debt			900
Preferred Stock [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Preferred stock issuance		$ 1,265	0	$ 0
Payments for repurchase of redeemable preferred stock	$ 1,265		$ 300
HSBC USA preferred stock issued (shares)		1,265	0	0
Common Stock [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
HSBC USA preferred stock issued (shares)		0	1	0
Common Stock [Member] | HSBC USA Inc [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
HSBC USA preferred stock issued (shares)			1
Common Stock [Member] | HSBC Bank USA, National Association [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
HSBC USA preferred stock issued (shares)			2
Capital distribution to subsidiary			$ 2,400
Hnah [Member] | 6.0% Non-Cumulative Preferred Stock, Series I ($1,000,000 stated value)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
HSBC USA preferred stock dividend rate (percent)	6.00%
Preferred stock issuance	$ 1,265
HSBC USA preferred stock issued (shares)	1,265