Postretirement benefits (Tables)

3 Months Ended

Mar. 31, 2016

Compensation and Retirement Disclosure [Abstract]

Schedule of Assumptions Used [Table Text Block]

The weighted average assumptions used to determine net pension and other postretirement benefit costs were as follows:

	Pension Benefits				Other Postretirement Benefits
	U.S. Plans		Non-U.S. Plans		U.S. Plans		Non-U.S. Plans
As of March 31, 2016
Discount rate	4.28	%	3.74	%	4.41	%	4.30	%
Rate of compensation increase	4.00	%	3.40	%	N/A		N/A
Expected long-term rate of return on plan assets	7.00	%	4.90	%	7.00	%	N/A
As of December 31, 2015
Discount rate	N/A		3.51	%	N/A		N/A
Rate of compensation increase	N/A		3.09	%	N/A		N/A
Expected long-term rate of return on plan assets	N/A		4.81	%	N/A		N/A

Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block]

	Pension Benefits									Other Postretirement Benefits
	U.S. Plans			Non U.S. Plans			Total			U.S. Plans			Non U.S. Plans			Total
(in millions of U.S. dollars)
Fair value of plan assets	$	2,473		$	315		$	2,788		$	138		$	—		$	138
Benefit obligation	(3,153		)	(372		)	(3,525		)	(491		)	(15		)	(506		)
Funded status	$	(680	)	$	(57	)	$	(737	)	$	(353	)	$	(15	)	$	(368	)

Schedule of Net Benefit Costs [Table Text Block]

The following table summarizes the components of net periodic benefit costs for our pension and postretirement benefit plans recognized in the consolidated statements of operations:

	Pension Benefits									Other Postretirement Benefits
(in millions of U.S. dollars)	U.S. Plans			Non-U.S. Plans			Total			U.S. Plans			Non-U.S. Plans		Total
Three months ended March 31, 2016
Net periodic benefit cost:
Service cost	$	17		$	5		$	22		$	2		$	—	$	2
Interest cost	27			8			35			5			—		5
Expected return on plan assets	(37		)	(10		)	(47		)	(2		)	—		(2		)
Amortization of unrecognized:
Net actuarial loss	—			1			1			—			—		—
Net periodic benefit cost	$	7		$	4		$	11		$	5		$	—	$	5
Three months ended March 31, 2015
Net periodic benefit cost:
Service cost	$	—		$	2		$	2
Interest cost	—			5			5
Expected return on plan assets	—			(7		)	(7		)
Amortization of unrecognized:
Net actuarial loss	—			1			1
Net periodic benefit cost	$	—		$	1		$	1