Related Party Transactions - Additional Information (Details) (USD $)									9 Months Ended																3 Months Ended		9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 HSBC Investment Bahamas [Member]	Dec. 31, 2013 HSBC Investment Bahamas [Member]	Sep. 30, 2014 HSBC North America Inc. HNAI [Member]	Dec. 31, 2013 HSBC North America Inc. HNAI [Member]	Sep. 30, 2014 HSBC Finance Corporation [Member]	Dec. 31, 2013 HSBC Finance Corporation [Member]	Sep. 30, 2014 HSBC Finance Corporation [Member] Extended Uncommitted Revolving Credit Facility [Member]	Dec. 31, 2013 HSBC Finance Corporation [Member] Extended Uncommitted Revolving Credit Facility [Member]	Sep. 30, 2014 HSBC Finance Corporation [Member] Extended committed revolving credit facility [Member]	Dec. 31, 2013 HSBC Finance Corporation [Member] Extended committed revolving credit facility [Member]	Sep. 30, 2014 HMUS [Member]	Dec. 31, 2013 HMUS [Member]	Sep. 30, 2014 HSBC Bank Brasil [Member]	Dec. 31, 2013 HSBC Bank Brasil [Member]	Sep. 30, 2014 Other Affiliates [Member]	Dec. 31, 2013 Other Affiliates [Member]	Sep. 30, 2014 Regency [Member]	Sep. 30, 2014 Affiliated Entity [Member]	Dec. 31, 2013 Affiliated Entity [Member]	Sep. 30, 2014 Residential Mortgage [Member] HSBC Finance Corporation [Member]	Dec. 31, 2013 Residential Mortgage [Member] HSBC Finance Corporation [Member]	Sep. 30, 2014 90-Day LIBOR Plus Spread [Member] Floating Rate Note [Member] Hnah [Member] Senior Notes [Member]	Sep. 30, 2014 Support Services From Affiliates [Member] Affiliated Entity [Member]	Sep. 30, 2013 Support Services From Affiliates [Member] Affiliated Entity [Member]	Sep. 30, 2014 Support Services From Affiliates [Member] Affiliated Entity [Member]	Sep. 30, 2013 Support Services From Affiliates [Member] Affiliated Entity [Member]	Sep. 30, 2014 Debt Maturing August 2015 [Member] 90-Day LIBOR Plus Spread [Member] Floating Rate Note [Member] Hnah [Member] Senior Notes [Member]	Sep. 30, 2014 Debt Maturing October 2015 [Member] 90-Day LIBOR Plus Spread [Member] Floating Rate Note [Member] Hnah [Member] Senior Notes [Member]
Related Party Transaction [Line Items]
Senior debt																								$ 4,000,000,000					$ 1,000,000,000	$ 3,000,000,000
Debt term									364 days
Maximum borrowing capacity			1,000,000,000	1,000,000,000	150,000,000	150,000,000
Extended loans and lines of credit									5,000,000,000		1,000,000,000	1,000,000,000	6,700,000,000	3,800,000,000	1,300,000,000	1,500,000,000	2,300,000,000	2,300,000,000
Loans and Leases Receivable, Related Parties							3,014,000,000	3,015,000,000					559,000,000	199,000,000	1,103,000,000	1,000,000,000	136,000,000	1,114,000,000		4,812,000,000	5,328,000,000
Loan And Lease Receivable Revolving Line Of Credit Outstanding									3,000,000,000	3,000,000,000	0	0	559,000,000	199,000,000	1,100,000,000	1,000,000,000	0	0
Maximum maturity for borrowings under uncommitted revolving credit agreement									5 years
Amount outstanding under the loan agreement			0	0	0	0
Credit agreement, amount maturing September 2017									512,000,000
Credit agreement amount maturing January 2018									1,500,000,000
Credit agreement amount maturing September 2018									1,000,000,000
Related Party Transaction, Liquidity Facility, Notional Amount																			2,400,000,000
Derivative, notional amount	5,070,299,000,000	5,457,095,000,000																		1,119,100,000,000	1,210,600,000,000
Fair value of derivative assets and liabilities																				649,000,000	845,000,000
Carrying Amount At Period End of Residential Mortgage Loans Serviced By HSBC Finance																						867,000,000	983,000,000
Rent from related party																									$ 14,000,000	$ 12,000,000	$ 41,000,000	$ 37,000,000