Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value of Financial Instruments [Abstract]

Fair value of financial assets and liabilities on a recurring basis

The Company's assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of fair value assets and liabilities and their placement within the fair value hierarchy levels.

(millions of dollars)			Fair Value Measurements Using
	Asset / (Liability) Balance at		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Description	December 31, 2018		(Level 1)		(Level 2)		(Level 3)
Deferred compensation plan assets	$	12.6	$	—	$	12.6	$	—
Supplementary pension plan assets		10.8		—		10.8		—
Cross currency rate swap		3.7		—		3.7		—
Interest rate swaps		0.3		—		0.3		—

			Fair Value Measurements Using
	Asset / (Liability) Balance at		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Description	December 31, 2017		(Level 1)		(Level 2)		(Level 3)
Deferred compensation plan assets	$	12.9	$	—	$	12.9	$	—
Supplementary pension plan assets		11.6		—		11.6		—
Interest rate swap		2.9		—		2.9		—
Money market funds		0.7		0.7		—		—