Derivative Financial Instruments - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Notional values of derivative contracts	$ 8,933	$ 13,980
Fair value of collateral agreements with affiliate counterparties	491	213
Decrease in debt carrying value due to fair value hedge	15	8
Losses on current derivative instruments designated as cash flow hedges are reported in OCI net of tax and totaled a loss	15	52
Unrealized net losses on cash flow hedges	17
Unrealized net losses on cash flow hedges after tax	11
HSBC Bank USA [Member]
Derivative [Line Items]
Notional values of derivative contracts	8,900	14,000
Derivatives not designated as hedging instruments [Member]
Derivative [Line Items]
Notional values of derivative contracts	2,624	$ 3,199
Notional value of terminated derivative	$ 575