Supplemental Cash Flow Information (Tables)

12 Months Ended

Dec. 31, 2016

Supplemental Cash Flow Elements [Abstract]

Supplemental Cash Flow Information

	Year Ended December 31,
	2016		2015		2014
	(in millions of dollars)
Interest paid	$	17.7	$	22.1	$	25.6
Non-cash investing and financing activities:
Stock repurchases not yet settled (accrued in accounts payable)	$	1.8	$	0.2	$	0.8
Unpaid purchases of property and equipment	$	4.6	$	10.5	$	1.8
Purchases of property and equipment through capital leasing arrangements	$	0.2	$	—	$	—