Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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Name:	us-gaap_RestrictedCashAndCashEquivalents
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Retained Earnings and Regulatory Capital Requirements - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Restricted cash		$ 2,475
Return of capital to parent	$ 0	2,400	$ 0
HSBC Bank USA [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Return of capital to parent		2,400
HNAH [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Return of capital to parent		$ 2,400