CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Millions	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]
Balance at beginning of period at Dec. 31, 2012		$ 1,565
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred stock redemption		0
Balance at end of period at Dec. 31, 2013	$ 16,464	$ 1,565
Balance at beginning of period at Dec. 31, 2012			$ 0	$ 14,123	$ 1,363	$ 785
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Excess of consideration received over book value on sale of London Branch precious metals business to an HSBC affiliate, net of tax				0
Capital contribution from parent				0
Employee benefit plans				(17)
Net income (loss)	(338)				(338)
Cash dividends declared on preferred stock					(73)
Adjustment to add other-than-temporary impairment on securities held-to-maturity due to the consolidation of a variable interest entity, net of tax	67					(67)
Other comprehensive income (loss), net of tax	(877)					(877)
Balance at end of period at Dec. 31, 2013	14,899		$ 0	14,106	952	(159)
Number of shares at beginning of period (shares) at Dec. 31, 2012		25,947,500	713
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Number of shares of cumulative preferred stock redeemed (shares)		0
Number of shares of common stock issued to parent (shares)			0
Number of shares at end of period (shares) at Dec. 31, 2013		25,947,500	713
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred stock redemption		$ 0
Balance at end of period at Dec. 31, 2014	16,967	$ 1,565
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Excess of consideration received over book value on sale of London Branch precious metals business to an HSBC affiliate, net of tax				60
Capital contribution from parent				0
Employee benefit plans				4
Net income (loss)	354				354
Cash dividends declared on preferred stock					(73)
Adjustment to add other-than-temporary impairment on securities held-to-maturity due to the consolidation of a variable interest entity, net of tax	0					0
Other comprehensive income (loss), net of tax	158					158
Balance at end of period at Dec. 31, 2014	15,402		$ 0	14,170	1,233	(1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Number of shares of cumulative preferred stock redeemed (shares)		0
Number of shares of common stock issued to parent (shares)			0
Number of shares at end of period (shares) at Dec. 31, 2014		25,947,500	713
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred stock redemption		$ (300)
Balance at end of period at Dec. 31, 2015	20,525	$ 1,265
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Excess of consideration received over book value on sale of London Branch precious metals business to an HSBC affiliate, net of tax				0
Capital contribution from parent				4,000
Employee benefit plans				(1)
Net income (loss)	330				330
Cash dividends declared on preferred stock					(65)
Adjustment to add other-than-temporary impairment on securities held-to-maturity due to the consolidation of a variable interest entity, net of tax	0					0
Other comprehensive income (loss), net of tax	(406)					(406)
Balance at end of period at Dec. 31, 2015	$ 19,260		$ 0	$ 18,169	$ 1,498	$ (407)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Number of shares of cumulative preferred stock redeemed (shares)		(4,500,000)
Number of shares of common stock issued to parent (shares)			1
Number of shares at end of period (shares) at Dec. 31, 2015		21,447,500	714