Retained Earnings and Regulatory Capital Requirements - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2016	Sep. 30, 2016	Sep. 30, 2015
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	$ 1,265	$ 300
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%
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]
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]
Preferred stock, par value (usd per share)	$ 1,000
Hnah [Member] | 6.0 %, Non-Cumulative Series I Preferred Stock [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
HSBC USA preferred stock dividend rate (percent)	6.00%
HSBC USA preferred stock issued (shares)	1,265
HSBC USA preferred stock issued	$ 1,265
Preferred stock, redemption price per share (usd per share)	$ 1,000,000