Related Party Transactions - Summary of Related Party Transactions (Details) - USD ($) $ in Millions		Sep. 30, 2018		Dec. 31, 2017		Sep. 30, 2017
Assets:
Cash and due from banks		$ 1,336		$ 1,115		$ 986
Interest bearing deposits with banks		20,306		11,157
Securities purchased under agreements to resell		4,679		32,618
Trading assets		26,556		16,150
Loans		66,756		72,563		67,593
Other		6,528		7,129
Total assets		174,002	[1]	187,235	[1]	197,886
Liabilities:
Deposits		112,090	[2]	118,702		121,840
Trading liabilities		3,948		4,879
Short-term borrowings		4,793		4,650
Long-term debt		29,516		34,966
Other		3,655		3,944
Total liabilities	[1]	154,002		167,141
Affiliated Entity [Member]
Assets:
Cash and due from banks		284		191
Interest bearing deposits with banks		309		473
Securities purchased under agreements to resell	[3]	0		1,115
Trading assets		94		63
Loans		1,557		6,750		$ 1,820
Other	[4]	330		134
Total assets		2,574		8,726
Liabilities:
Deposits		14,189		10,521
Trading liabilities		174		737
Short-term borrowings		710		1,595
Long-term debt		4,844		4,841
Other	[4]	271		387
Total liabilities		$ 20,188		$ 18,081

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at September 30, 2018 and December 31, 2017 which are consolidated on our balance sheet. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 17, "Variable Interest Entities," for additional information. Assets: Other assets $121 million and $154 million. Total assets $121 million and $154 million respectively. Liabilities: Long-term debt $73 million and $73 million, Interest, taxes and other liabilities $61 million and $59 million. Total liabilities $134 million and $132 million, respectively.

[2] In addition to the changes discussed above, in conjunction with HSBC's adoption of the requirements of IFRS 9 we also adopted changes in presentation under the Group Reporting Basis related to affiliate loans and deposits as well as cash collateral posted and received. Beginning January 1, 2018, affiliate loans have been reclassified from other assets to loans, affiliate deposits have been reclassified from other liabilities to deposits, cash collateral posted has been reclassified from loans to other assets and cash collateral received has been reclassified from deposits to other liabilities. As a result of these changes, total loans, net and total deposits in the GB&M segment increased $0.2 billion and $8.6 billion, respectively, and total loans, net and total deposits in the CC segment decreased $2.0 billion and $1.5 billion, respectively, at September 30, 2018.

[3] Reflects purchases of securities which other HSBC affiliates have agreed to repurchase.

[4] Other assets and other liabilities primarily consist of derivative balances associated with hedging activities and other miscellaneous account receivables and payables.