Long-Term Debt Long Term Debt Table (Details) (USD $) In Millions, unless otherwise specified																																	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Secured Debt [Member] 5.00%-5.99% Fixed Rate Senior Debt Due 2014-2017 [Member]	Dec. 31, 2011 Secured Debt [Member] 5.00%-5.99% Fixed Rate Senior Debt Due 2014-2017 [Member]	Dec. 31, 2012 Other Fixed Rate Senior Debt [Member] 1.00%-1.99% Other Fixed Rate Senior Debt Due 2013-2014 [Member]	Dec. 31, 2011 Other Fixed Rate Senior Debt [Member] 1.00%-1.99% Other Fixed Rate Senior Debt Due 2013-2014 [Member]	Dec. 31, 2012 Other Fixed Rate Senior Debt [Member] 2.00%-2.99% Other Fixed Rate Senior Debt Due 2013-2032 [Member]	Dec. 31, 2011 Other Fixed Rate Senior Debt [Member] 2.00%-2.99% Other Fixed Rate Senior Debt Due 2013-2032 [Member]	Dec. 31, 2012 Other Fixed Rate Senior Debt [Member] 3.00%-3.99% Other Fixed Rate Senior Debt Due 2012-2016 [Member]	Dec. 31, 2011 Other Fixed Rate Senior Debt [Member] 3.00%-3.99% Other Fixed Rate Senior Debt Due 2012-2016 [Member]	Dec. 31, 2012 Other Fixed Rate Senior Debt [Member] 4.00%-4.99% Other Fixed Rate Senior Debt Due 2012-2018 [Member]	Dec. 31, 2011 Other Fixed Rate Senior Debt [Member] 4.00%-4.99% Other Fixed Rate Senior Debt Due 2012-2018 [Member]	Dec. 31, 2012 Other Fixed Rate Senior Debt [Member] 5.00%-5.49% Other Fixed Rate Senior Debt Due 2012-2021 [Member]	Dec. 31, 2011 Other Fixed Rate Senior Debt [Member] 5.00%-5.49% Other Fixed Rate Senior Debt Due 2012-2021 [Member]	Dec. 31, 2012 Other Fixed Rate Senior Debt [Member] 5.50%-5.99% Other Fixed Rate Senior Debt Due 2012-2018 [Member]	Dec. 31, 2011 Other Fixed Rate Senior Debt [Member] 5.50%-5.99% Other Fixed Rate Senior Debt Due 2012-2018 [Member]	Dec. 31, 2012 Other Fixed Rate Senior Debt [Member] 6.00%-6.49% Other Fixed Rate Senior Debt Due 2012-2017 [Member]	Dec. 31, 2011 Other Fixed Rate Senior Debt [Member] 6.00%-6.49% Other Fixed Rate Senior Debt Due 2012-2017 [Member]	Dec. 31, 2012 Other Fixed Rate Senior Debt [Member] 6.50%-6.99% Other Fixed Rate Senior Debt Due 2012-2013 [Member]	Dec. 31, 2011 Other Fixed Rate Senior Debt [Member] 6.50%-6.99% Other Fixed Rate Senior Debt Due 2012-2013 [Member]	Dec. 31, 2012 Other Fixed Rate Senior Debt [Member] 7.00%-7.49% Other Fixed Rate Senior Debt Due 2012-2032 [Member]	Dec. 31, 2011 Other Fixed Rate Senior Debt [Member] 7.00%-7.49% Other Fixed Rate Senior Debt Due 2012-2032 [Member]	Dec. 31, 2012 Other Fixed Rate Senior Debt [Member] 7.50%-7.99 Other Fixed Rate Senior Debt Due 2012-2032 [Member]	Dec. 31, 2011 Other Fixed Rate Senior Debt [Member] 7.50%-7.99 Other Fixed Rate Senior Debt Due 2012-2032 [Member]	Dec. 31, 2012 Variable Interest Rate Debt [Member] .36%-2.78% Secured Financings Due 2012-2019 [Member]	Dec. 31, 2011 Variable Interest Rate Debt [Member] .36%-2.78% Secured Financings Due 2012-2019 [Member]	Dec. 31, 2012 Variable Interest Rate Debt [Member] .59%-5.94% Other Variable Interest Rate Senior Debt Due 2012-2016 [Member]	Dec. 31, 2011 Variable Interest Rate Debt [Member] .59%-5.94% Other Variable Interest Rate Senior Debt Due 2012-2016 [Member]	Dec. 31, 2012 Subordinated Debt [Member]	Dec. 31, 2011 Subordinated Debt [Member]	Dec. 31, 2012 Junior subordinated notes issued to capital trusts [Member]	Dec. 31, 2011 Junior subordinated notes issued to capital trusts [Member]	Dec. 31, 2012 Minimum [Member] Secured Debt [Member] 5.00%-5.99% Fixed Rate Senior Debt Due 2014-2017 [Member]	Dec. 31, 2012 Minimum [Member] Other Fixed Rate Senior Debt [Member] 1.00%-1.99% Other Fixed Rate Senior Debt Due 2013-2014 [Member]	Dec. 31, 2012 Minimum [Member] Other Fixed Rate Senior Debt [Member] 2.00%-2.99% Other Fixed Rate Senior Debt Due 2013-2032 [Member]	Dec. 31, 2012 Minimum [Member] Other Fixed Rate Senior Debt [Member] 3.00%-3.99% Other Fixed Rate Senior Debt Due 2012-2016 [Member]	Dec. 31, 2012 Minimum [Member] Other Fixed Rate Senior Debt [Member] 4.00%-4.99% Other Fixed Rate Senior Debt Due 2012-2018 [Member]	Dec. 31, 2012 Minimum [Member] Other Fixed Rate Senior Debt [Member] 5.00%-5.49% Other Fixed Rate Senior Debt Due 2012-2021 [Member]	Dec. 31, 2012 Minimum [Member] Other Fixed Rate Senior Debt [Member] 5.50%-5.99% Other Fixed Rate Senior Debt Due 2012-2018 [Member]	Dec. 31, 2012 Minimum [Member] Other Fixed Rate Senior Debt [Member] 6.00%-6.49% Other Fixed Rate Senior Debt Due 2012-2017 [Member]	Dec. 31, 2012 Minimum [Member] Other Fixed Rate Senior Debt [Member] 6.50%-6.99% Other Fixed Rate Senior Debt Due 2012-2013 [Member]	Dec. 31, 2012 Minimum [Member] Other Fixed Rate Senior Debt [Member] 7.00%-7.49% Other Fixed Rate Senior Debt Due 2012-2032 [Member]	Dec. 31, 2012 Minimum [Member] Other Fixed Rate Senior Debt [Member] 7.50%-7.99 Other Fixed Rate Senior Debt Due 2012-2032 [Member]	Dec. 31, 2012 Minimum [Member] Variable Interest Rate Debt [Member] .36%-2.78% Secured Financings Due 2012-2019 [Member]	Dec. 31, 2012 Minimum [Member] Variable Interest Rate Debt [Member] .59%-5.94% Other Variable Interest Rate Senior Debt Due 2012-2016 [Member]	Dec. 31, 2012 Maximum [Member] Secured Debt [Member] 5.00%-5.99% Fixed Rate Senior Debt Due 2014-2017 [Member]	Dec. 31, 2012 Maximum [Member] Other Fixed Rate Senior Debt [Member] 1.00%-1.99% Other Fixed Rate Senior Debt Due 2013-2014 [Member]	Dec. 31, 2012 Maximum [Member] Other Fixed Rate Senior Debt [Member] 2.00%-2.99% Other Fixed Rate Senior Debt Due 2013-2032 [Member]	Dec. 31, 2012 Maximum [Member] Other Fixed Rate Senior Debt [Member] 3.00%-3.99% Other Fixed Rate Senior Debt Due 2012-2016 [Member]	Dec. 31, 2012 Maximum [Member] Other Fixed Rate Senior Debt [Member] 4.00%-4.99% Other Fixed Rate Senior Debt Due 2012-2018 [Member]	Dec. 31, 2012 Maximum [Member] Other Fixed Rate Senior Debt [Member] 5.00%-5.49% Other Fixed Rate Senior Debt Due 2012-2021 [Member]	Dec. 31, 2012 Maximum [Member] Other Fixed Rate Senior Debt [Member] 5.50%-5.99% Other Fixed Rate Senior Debt Due 2012-2018 [Member]	Dec. 31, 2012 Maximum [Member] Other Fixed Rate Senior Debt [Member] 6.00%-6.49% Other Fixed Rate Senior Debt Due 2012-2017 [Member]	Dec. 31, 2012 Maximum [Member] Other Fixed Rate Senior Debt [Member] 6.50%-6.99% Other Fixed Rate Senior Debt Due 2012-2013 [Member]	Dec. 31, 2012 Maximum [Member] Other Fixed Rate Senior Debt [Member] 7.00%-7.49% Other Fixed Rate Senior Debt Due 2012-2032 [Member]	Dec. 31, 2012 Maximum [Member] Other Fixed Rate Senior Debt [Member] 7.50%-7.99 Other Fixed Rate Senior Debt Due 2012-2032 [Member]	Dec. 31, 2012 Maximum [Member] Variable Interest Rate Debt [Member] .36%-2.78% Secured Financings Due 2012-2019 [Member]	Dec. 31, 2012 Maximum [Member] Variable Interest Rate Debt [Member] .59%-5.94% Other Variable Interest Rate Senior Debt Due 2012-2016 [Member]	Dec. 31, 2011 HSBC North America [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross			$ 189	$ 270	$ 16	$ 16	$ 347	$ 892	$ 422	$ 534	$ 3,675	$ 3,774	$ 6,156	$ 8,042	$ 2,638	$ 3,643	$ 1,818	$ 3,334	$ 2	$ 8	$ 42	$ 1,724	$ 284	$ 1,071	$ 2,689	$ 3,045	$ 6,932	$ 10,229	$ 2,208	$ 2,208	$ 1,031	$ 1,031
Unamortized Discount	(54)	(67)
HSBC acquisition purchase accounting fair value adjustments	31	36
Long-term debt	$ 28,426	$ 39,790																																																									$ 600
Debt Instrument, Interest Rate, Stated Percentage																															5.91%		5.00%	1.00%	2.00%	3.00%	4.00%	5.00%	5.50%	6.00%	6.50%	7.00%	7.50%	0.36%	0.59%	5.99%	1.99%	2.99%	3.99%	4.99%	5.49%	5.99%	6.49%	6.99%	7.49%	7.99%	2.78%	5.94%
Debt Instrument, Maturity Year																																	2014	2013	2013	2012	2012	2012	2012	2012	2012	2012	2012	2012	2012	2017	2014	2032	2016	2018	2021	2018	2017	2013	2032	2032	2019	2016