Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2018

Benefit Plans [Abstract]

Net Periodic Benefit Cost

Components of Net Periodic Benefit Cost

	Pension Benefits
	Three Months Ended						Nine Months Ended
(millions of dollars)	Sep. 30, 2018			Oct. 1, 2017			Sep. 30, 2018			Oct. 1, 2017
Service cost	$	1.9		$	1.4		$	5.8		$	5.5
Interest cost		3.2			3.0			9.3			9.2
Expected return on plan assets		(5.0	)		(4.5	)		(14.6	)		(13.6	)
Amortization:
Prior service cost		0.1			0.5			0.3			1.7
Recognized net actuarial loss		2.9			2.1			8.4			6.3
Pension settlement loss		3.6			—			3.6			—
Net periodic benefit cost	$	6.7		$	2.5		$	12.8		$	9.1

	Other Benefits
	Three Months Ended						Nine Months Ended
(millions of dollars)	Sep. 30, 2018			Oct. 1, 2017			Sep. 30, 2018			Oct. 1, 2017
Service cost	$	0.1		$	0.1		$	0.2		$	0.2
Interest cost		—			0.1			0.1			0.2
Amortization:
Prior service cost		(0.2	)		(0.8	)		(0.7	)		(2.3	)
Recognized net actuarial (gain) loss		(0.2	)		(0.1	)		(0.5	)		(0.2	)
Net periodic benefit cost	$	(0.3	)	$	(0.7	)	$	(0.9	)	$	(2.1	)