Related Party Transactions - Summary of Related Party Transactions (Details) - USD ($) $ in Millions		Mar. 31, 2018		Dec. 31, 2017		Mar. 31, 2017
Assets:
Cash and due from banks		$ 1,053		$ 1,115		$ 1,037
Interest bearing deposits with banks		17,895		11,157
Securities purchased under agreements to resell		9,814		32,618
Trading assets		32,650		16,150
Loans		67,338		72,563		69,588
Other		7,137		7,129
Total assets		182,035	[1]	187,235	[1]	201,583
Liabilities:
Deposits		117,953	[2]	118,702		129,258
Trading liabilities		3,330		4,879
Short-term borrowings		5,138		4,650
Long-term debt		32,008		34,966
Other		3,923		3,944
Total liabilities	[1]	162,352		167,141
Affiliated Entity [Member]
Assets:
Cash and due from banks		279		191
Interest bearing deposits with banks		709		473
Securities purchased under agreements to resell	[3]	181		1,115
Trading assets		103		63
Loans		1,920		6,750		$ 939
Other	[4]	221		134
Total assets		3,413		8,726
Liabilities:
Deposits		14,001		10,521
Trading liabilities		0		737
Short-term borrowings		1,296		1,595
Long-term debt		4,842		4,841
Other	[4]	465		387
Total liabilities		$ 20,604		$ 18,081

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at March 31, 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 $146 million and $154 million. Total assets $146 million and $154 million respectively. Liabilities: Long-term debt $73 million and $73 million, Interest, taxes and other liabilities $59 million and $59 million. Total liabilities $132 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 $10.8 billion, respectively, and total loans, net and total deposits in the CC segment decreased $3.0 billion and $0.9 billion, respectively, at March 31, 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.