Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2019

Benefit Plans [Abstract]

Net Periodic Benefit Cost

Components of Net Periodic Benefit Cost

	Pension Benefits
	Three Months Ended						Six Months Ended
(millions of dollars)	June 30, 2019			July 1, 2018			June 30, 2019			July 1, 2018
Service cost	$	1.8		$	2.0		$	3.6		$	3.9
Interest cost		3.6			3.0			7.1			6.1
Expected return on plan assets		(4.6	)		(4.8	)		(9.2	)		(9.6	)
Amortization:
Prior service cost		0.1			0.1			0.2			0.2
Recognized net actuarial loss		2.3			2.7			4.6			5.5
Net periodic benefit cost	$	3.2		$	3.0		$	6.3		$	6.1

	Other Benefits
	Three Months Ended						Six Months Ended
(millions of dollars)	June 30, 2019			July 1, 2018			June 30, 2019			July 1, 2018
Service cost	$	0.1		$	0.1		$	0.1		$	0.1
Interest cost		—			—			0.1			0.1
Amortization:
Prior service cost		—			(0.2	)		—			(0.4	)
Recognized net actuarial (gain) loss		(0.2	)		(0.2	)		(0.4	)		(0.4	)
Net periodic benefit cost	$	(0.1	)	$	(0.3	)	$	(0.2	)	$	(0.6	)