Income Taxes - Net Deferred Tax Position (Details) - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Allowance for credit losses		$ 245	$ 153
Accrued expenses		108	76
Interests in real estate mortgage investment conduits	[1]	158	181
Unrealized losses on investment securities		0	36
Capitalized costs	[2]	501	595
Lease liabilities		152	190
Other		268	285
Total deferred tax assets		1,432	1,516
Valuation allowance		0	(8)
Total deferred tax assets, net of valuation allowance		1,432	1,508
Deferred tax liabilities:
Lease ROU assets		127	172
Unrealized gains on investment securities		237	0
Other		57	36
Total deferred tax liabilities		421	208
Net deferred tax asset		$ 1,011	$ 1,300

[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.

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