Segment Reporting - Segment Reporting Information by Operating Segment (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2016	Oct. 01, 2016	Jul. 02, 2016	Apr. 02, 2016	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
Segment Reporting Information [Line Items]
Revenue, net	$ 571.3	$ 580.9	$ 580.6	$ 536.9	$ 521.2	$ 476.7	$ 320.2	$ 305.1	$ 2,269.7	$ 1,623.2	$ 1,187.3
Operating Segments [Member] | All Other [Member]
Segment Reporting Information [Line Items]
Revenue, net									165.8	170.9	166.1
Operating Segments [Member] | Discontinued Operations, Disposed of by Sale [Member] | Concentrate [Member] | All Other [Member]
Segment Reporting Information [Line Items]
Revenue, net									$ 41.1	$ 37.4	$ 36.8