Discontinued Operations - Operating Results of Discontinued Operations (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended						0 Months Ended	3 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Mar. 29, 2013	Jun. 30, 2012	Mar. 31, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations before income tax	$ (27)		$ (249)		$ 2,521
Insurance business [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net interest income and other revenues	0	[1],[2]	70	[1],[2]	167	[1],[2]
Income (loss) from discontinued operations before income tax	0	[2]	(10)	[2]	(162)	[2]
Lower of amortized cost or fair value less cost to sell adjustment, before tax					119
Pre-tax gain							21
Commercial Business [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net interest income and other revenues	10		22		23
Income (loss) from discontinued operations before income tax	6		14		20
Card and Retail Services [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net interest income and other revenues	0	[1],[3]	1	[1],[3]	3,342	[1],[3]
Income (loss) from discontinued operations before income tax	(33)	[3],[4]	(253)	[3],[4]	2,649	[3]
Pre-tax gain								2,178
Incremental increase in industry review enhancement expense	7		87
Provision for legal expenses and other			40
Card and Retail Services [Member] | HSBC USA, Inc. [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of intangible assets									$ 79

[1] Interest expense, which is included as a component of net interest income, was allocated to discontinued operations in accordance with our existing internal transfer pricing policy. This policy uses match funding based on the expected lives of the assets and liabilities of the business at the time of origination, subject to periodic review, as demonstrated by the expected cash flows and re-pricing characteristics of the underlying assets.

[2] For the year ended December 31, 2012, amounts include the lower of amortized cost or fair value adjustment of $119 million, as discussed above, which was reported as a component of other revenues within discontinued operations.

[3] For 2012, amounts include the gain on sale to Capital One of $2,178 million. For 2012, amounts also include a gain of $79 million resulting from the sale of account relationships to HSBC Bank USA which we had previously purchased from HSBC Bank USA in July 2004.

[4] For 2014 and 2013, the amounts include expenses related to activities to complete the separation of the credit card operational infrastructure between us and Capital One. We expect costs associated with the separation of the credit card operational infrastructure to continue in 2015. Additionally, 2014 and 2013 include an incremental expense of $7 million and $87 million recorded based on actions taken and actions planned to be taken in connection with an industry review of enhancement services products. For 2013, amounts also reflect a legal accrual of $40 million. See Note 22, "Litigation and Regulatory Matters," for further discussion of the legal matter.