Pension and Other Postretirement Benefits (Tables)

12 Months Ended

Dec. 31, 2017

HSBC North America Pension Plan [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

Components of Net Periodic Benefit Cost

Year Ended December 31,	2017			2016			2015
	(in millions)
Interest cost on projected benefit obligation	$	71		$	70		$	70
Expected return on plan assets	(88		)	(86		)	(90		)
Amortization of net actuarial loss	33			42			38
Administrative costs	4			4			5
Loss on partial settlement of Plan pension obligation	35			—			—
Pension expense	$	55		$	30		$	23

Schedule of Assumptions Used [Table Text Block]

The assumptions used in determining pension expense of the HSBC North America Pension Plan are as follows:

	2017		2016		2015
Discount rate	3.60	%	4.25	%	3.95	%
Expected long-term rate of return on Plan assets	5.50		5.50		6.00

Postretirement Plans Other Than Pensions [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

Components of Net Periodic Benefit Cost

The following table reflects the components of the net periodic postretirement benefit cost:

Year Ended December 31,	2017			2016		2015
	(in millions)
Interest cost on accumulated benefit obligation	$	2		$	2	2
Amortization of net actuarial gain	(1		)	—		—
Net periodic postretirement benefit cost	$	1		$	2	$	2

Schedule of Assumptions Used [Table Text Block]

The assumptions used in determining the net periodic postretirement benefit cost for our postretirement benefit plans are as follows:

	2017		2016		2015
Discount rate	3.95	%	3.95	%	3.60	%
Salary increase assumption	3.00		3.00		3.00

The assumptions used in determining the benefit obligation of our postretirement benefit plans at December 31 are as follows:

	2017		2016		2015
Discount rate	3.45	%	3.95	%	3.95	%
Salary increase assumption	3.00		3.00		3.00

Schedule of Accumulated and Projected Benefit Obligations [Table Text Block]

A reconciliation of the beginning and ending balances of the accumulated postretirement benefit obligation is as follows:

	2017			2016
	(in millions)
Accumulated benefit obligation at beginning of year	$	55		$	60
Interest cost	2			2
Actuarial losses (gains)	—			(3		)
Benefits paid, net	(4		)	(4		)
Accumulated benefit obligation at end of year	$	53		$	55

Schedule of Expected Benefit Payments [Table Text Block]

Estimated future benefit payments for our postretirement benefit plans are summarized in the following table:

	(in millions)
2018	$	4
2019	4
2020	4
2021	4
2022	4
2023-2027	18