Pensions and Other Postretirement Benefits-Total Net Assets (Details) (Hsbc North America [Member], HSBC North America Pension Plan [Member], USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Total Net Assets	$ 3,875		$ 3,435		$ 3,485
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	1,470		1,443
Liabilities	(126)		(111)
Total Net Assets	1,344		1,332
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	2,503		2,196
Liabilities	(1)		(124)
Total Net Assets	2,502		2,072
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	29		31
Liabilities	0		0
Total Net Assets	29		31
Investments [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	1,346		1,337
Investments [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	2,487		2,191
Investments [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	29		31
Cash and short-term investments [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	81		106
Cash and short-term investments [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
Cash and short-term investments [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
U.S. Large-cap [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	330	[1]	303	[1]
U.S. Large-cap [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	[1]	0	[1]
U.S. Large-cap [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	[1]	0	[1]
U.S. Small-cap [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	106	[2]	104	[2]
U.S. Small-cap [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	[2]	0	[2]
U.S. Small-cap [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	[2]	0	[2]
International [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	36	[3]	28	[3]
International [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	265	[3]	282	[3]
International [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	[3]	0	[3]
Global Equity [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	103	[4]	65
Global Equity [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	166	[4]	322
Global Equity [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	[4]	0
Emerging Market [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	[5]	0	[5]
Emerging Market [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	205	[5]	206	[5]
Emerging Market [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	[5]	0	[5]
U.S. Treasury [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	646		716
U.S. Treasury [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
U.S. Treasury [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
US Government agency issued or guaranteed [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		9
US Government agency issued or guaranteed [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	91		74
US Government agency issued or guaranteed [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
Obligations of U.S. states and political subdivision [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
Obligations of U.S. states and political subdivision [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	109		70
Obligations of U.S. states and political subdivision [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
Asset backed securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
Asset backed securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	12		11
Asset backed securities [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	20		20
U.S. corporate debt securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	[6]	0	[6]
U.S. corporate debt securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	1,117	[6]	827	[6]
U.S. corporate debt securities [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0	[6]	0	[6]
Foreign debt securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
Foreign debt securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	307		268
Foreign debt securities [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	9		11
Emerging Market Debt/High-Yield Debt/Leveraged Loans [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	39
Emerging Market Debt/High-Yield Debt/Leveraged Loans [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	92
Emerging Market Debt/High-Yield Debt/Leveraged Loans [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0
Other investments [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
Other investments [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	103		114
Other investments [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
Accrued interest [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	5		6
Accrued interest [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	20		17
Accrued interest [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
Investment Receivable [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	124		106
Investment Receivable [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	16		5
Investment Receivable [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
Receivables from sale of investments in process of settlement [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	124		106
Receivables from sale of investments in process of settlement [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
Receivables from sale of investments in process of settlement [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
Derivative financial assets [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
Derivative financial assets [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	16		5
Derivative financial assets [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	0		0
Derivative Liabilities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Liabilities	(8)		(13)
Derivative Liabilities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Liabilities	(1)		(124)
Derivative Liabilities [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Liabilities	0		0
Other Liabilities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Liabilities	(118)		(98)
Other Liabilities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Liabilities	0		0
Other Liabilities [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Liabilities	0		0
Estimate of fair value [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	4,002		3,670
Liabilities	(127)		(235)
Total Net Assets	3,875		3,435
Estimate of fair value [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	3,862		3,559
Estimate of fair value [Member] | Cash and short-term investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	81		106
Estimate of fair value [Member] | U.S. Large-cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	330	[1]	303	[1]
Estimate of fair value [Member] | U.S. Small-cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	106	[2]	104	[2]
Estimate of fair value [Member] | International [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	301	[3]	310	[3]
Estimate of fair value [Member] | Global Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	269	[4]	387
Estimate of fair value [Member] | Emerging Market [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	205	[5]	206	[5]
Estimate of fair value [Member] | U.S. Treasury [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	646		716
Estimate of fair value [Member] | US Government agency issued or guaranteed [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	91		83
Estimate of fair value [Member] | Obligations of U.S. states and political subdivision [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	109		70
Estimate of fair value [Member] | Asset backed securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	32		31
Estimate of fair value [Member] | U.S. corporate debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	1,117	[6]	827	[6]
Estimate of fair value [Member] | Foreign debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	316		279
Estimate of fair value [Member] | Emerging Market Debt/High-Yield Debt/Leveraged Loans [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	131
Estimate of fair value [Member] | Other investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	103		114
Estimate of fair value [Member] | Accrued interest [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	25		23
Estimate of fair value [Member] | Investment Receivable [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	140		111
Estimate of fair value [Member] | Receivables from sale of investments in process of settlement [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	124		106
Estimate of fair value [Member] | Derivative financial assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Assets	16		5
Estimate of fair value [Member] | Derivative Liabilities [Member]
Defined Benefit Plan Disclosure [Line Items]
Liabilities	(9)		(137)
Estimate of fair value [Member] | Other Liabilities [Member]
Defined Benefit Plan Disclosure [Line Items]
Liabilities	$ (118)		$ (98)

[1] This category comprises actively managed enhanced index investments that track the S&P 500 and actively managed U.S. investments that track the Russell 1000.

[2] This category comprises actively managed U.S. investments that track the Russell 2000.

[3] This category comprises actively managed equity investments in non-U.S. and Canada developed markets that are primarily large-cap, and generally track the MSCI EAFE index. MSCI EAFE is an equity market index of 21 developed market countries in Europe, Australia, Asia and the Far East including Australia, Austria, Belgium, Denmark, Finland, France, Germany, Hong Kong, Ireland, Israel, Italy, Japan, the Netherlands, New Zealand, Norway, Portugal, Singapore, Spain, Sweden, Switzerland, and the United Kingdom.

[4] This category comprises actively and passively managed global investments that track the MSCI AC World Index.

[5] This category comprises actively managed emerging market investments that track the MSCI Emerging Markets Index.

[6] This category represents predominantly investment grade bonds of U.S. issuers from diverse industries.