Summary of significant accounting policies Summary of Significant Accounting Policies (Tables) (Tables)

12 Months Ended

Dec. 31, 2018

Cash and Cash Equivalents [Abstract]

Schedule of Cash and Cash Equivalents [Table Text Block]

The following table provides a reconciliation of cash and restricted cash reported within the Consolidated balance sheets that total to the amounts shown in the Consolidated statements of cash flows:

	December 31
(in millions of U.S. dollars)	2018		2017		2016
Cash	$	1,247	$	728	$	985
Restricted cash	93		123		103
Total cash and restricted cash shown in the Consolidated statements of cash flows	$	1,340	$	851	$	1,088