Other Financial Information (Tables)

6 Months Ended

Jun. 30, 2020

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Summary of Changes in Operating Working Capital

CHANGES IN WORKING CAPITAL:

	Six Months Ended June 30,
(Millions of dollars)	2020		2019
Accounts receivable	$	12.4	$	(97.5)
Inventories	(30.3)		10.2
Prepaid expenses and other current assets	12.4		(4.6)
Accounts payable and accrued liabilities	(12.1)		91.4
Income taxes payable	40.8		—
Net (increase) decrease in noncash operating working capital	$	23.2	$	(0.5)