Income Taxes - Net Deferred Tax Position (Details) - USD ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Allowance for credit losses		$ 166	$ 392
Employee benefit accruals		75	108
Accrued expenses		72	110
Interests in real estate mortgage investment conduits	[1]	175	548
Unrealized losses on investment securities		96	275
Partnerships		73	113
Capitalized costs	[2]	724	0
Fair value adjustments		26	0
Other		165	360
Total deferred tax assets		1,572	1,906
Valuation allowance		(6)	(6)
Total deferred tax assets, net of valuation allowance		1,566	1,900
Less deferred tax liabilities:
Fair value adjustments		0	48
Other		26	49
Total deferred tax liabilities		26	97
Net deferred tax asset		$ 1,540	$ 1,803

[1] Real estate mortgage investment conduits ("REMICs") are investment vehicles that hold commercial and residential mortgages in trust and issue securities representing an undivided interest in these mortgages. HSBC Bank USA holds portfolios of noneconomic residual interests in a number of REMICs. This item represents tax basis in such interests which has accumulated as a result of tax rules requiring the recognition of income related to such noneconomic residuals. In 2017, a substantial portion of our noneconomic residual interests were sold.

[2] Reflects our tax return election to capitalize certain service costs.