Fair Value Measurements (Tables)

9 Months Ended

Oct. 01, 2017

Fair Value Disclosures [Abstract]

Schedule of Fair Value Assets Measured on Recurring Basis

	Fair Value Measurements on a Recurring Basis As of Third Quarter-End 2017
Description	Total		Level 1		Level 2		Level 3
	(In millions of dollars)
Money market funds	$	4.2	$	4.2	$	—	$	—
Available-for-sale investment	212.4		212.4		—		—
Total assets at fair value	$	216.6	$	216.6	$	—	$	—

	Fair Value Measurements on a Recurring Basis As of Year-End 2016
Description	Total		Level 1		Level 2		Level 3
	(In millions of dollars)
Money market funds	$	4.0	$	4.0	$	—	$	—
Available-for-sale investment	141.2		141.2		—		—
Total assets at fair value	$	145.2	$	145.2	$	—	$	—