Pensions and Other Postretirement Benefits-Net Periodic Benefit Cost (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Postretirement Plans Other Than Pensions [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost – benefits earned during the period	$ 0	$ 1	$ 0	$ 1
Interest cost on projected benefit obligation	1	0	2	2
Amortization of transition obligation	0	1	0	2
Net periodic benefit cost	1	2	2	5
Parent [Member] | HSBC North America Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost – benefits earned during the period	1	4	3	11
Interest cost on projected benefit obligation	18	17	52	52
Expected return on assets	(19)	(23)	(60)	(66)
Amortization of prior service cost (benefit)	0	(1)	0	(4)
Recognized losses	10	13	36	34
Curtailment benefit recognized	0	(29)	0	(31)
Net periodic benefit cost	$ 10	$ (19)	$ 31	$ (4)