Pension and Other Postretirement Benefits - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Employer Matching Contribution Percentage	6.00%
Defined contribution plan expense	$ 6	$ 6	$ 4
Expected pension benefits in 2015	15
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions by Employer	74	131	181
Curtailment gain			4
Pension expense	18	29	14
Supplemental Employee Retirement Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected Benefit Obligation	48	54
Pension expense	7	7	17
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension expense	7	7	6
Expected pension benefits in 2015	15
Accumulated Benefit Obligation, continuing and discontinued operations	173	174	197
Health Care Cost Trend Rate Assumed, Participants under 65	7.00%
Health Care Cost Trend Rate Assumed, Participants over 65	6.70%
Ultimate Health Care Cost Trend Rate	4.50%
Year that Rate Reaches Ultimate Trend Rate	2027
HSBC North America [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated Benefit Obligation	$ 4,365	$ 3,892