Revenue - Schedule of Net Revenue to External Customers By Reportable Segment and Geographic Area Based on Customer Location (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Disaggregation of Revenue [Line Items]
Total	$ 560.8	$ 536.9
United States [Member]
Disaggregation of Revenue [Line Items]
Total	418.6	409.6
United Kingdom [Member]
Disaggregation of Revenue [Line Items]
Total	43.6	38.7
Canada [Member]
Disaggregation of Revenue [Line Items]
Total	15.2	14.5
Other Country [Member]
Disaggregation of Revenue [Line Items]
Total	$ 83.4	$ 74.1