Loans - Components of Loans (Details) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		$ 72,468	$ 68,553
Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		51,913	48,211
Commercial Loans [Member] | Real Estate, Including Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		11,420	11,501
Commercial Loans [Member] | Business and Corporate Banking [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	[1]	17,345	13,479
Loans funded under the Payroll Protection Program		1,197
Commercial Loans [Member] | Global Banking [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	[2]	18,668	17,915
Commercial Loans [Member] | Other Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		4,480	5,316
Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		20,555	20,342
Consumer Loans [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		18,281	17,801
Consumer Loans [Member] | Home Equity Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		792	853
Consumer Loans [Member] | Credit Cards [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		1,175	1,405
Consumer Loans [Member] | Other consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	[3]	307	283
Consumer Loans [Member] | Student Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, designated under fair value option		35
Affiliated Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		1,565	2,343
Affiliated Entity [Member] | Commercial Loans [Member] | Other Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	[4]	1,565	2,343
Other [Member] | Commercial Loans [Member] | Other Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		$ 2,915	$ 2,973

[1] Includes loans funded under the Paycheck Protection Program ("PPP") which totaled $1,197 million at June 30, 2020. PPP loans are fully guaranteed by the Small Business Administration, if certain conditions are met.

[2] Represents large multinational firms including globally focused U.S. corporate and financial institutions, U.S. dollar lending to multinational banking clients managed by HSBC on a global basis and complex large business clients supported by Global Banking and Markets relationship managers.

[3] Includes certain student loans that we have elected to designate under the fair value option and are therefore carried at fair value, which totaled $35 million at June 30, 2020. See Note 10, "Fair Value Option," for further details.

[4] See Note 14, "Related Party Transactions," for additional information regarding loans to HSBC affiliates.