Segment Disclosures - Summary of Long-Lived Assets By Geographic Area (Details) - USD ($) $ in Millions	Dec. 31, 2017	Jan. 01, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 86.1	$ 80.8
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	74.3	69.5
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 11.8	$ 11.3