Segment information - Long lived assets by geography (Details) - USD ($) $ in Millions	Jan. 02, 2021	Dec. 28, 2019
Revenues from External Customers and Long-Lived Assets
Long-Lived Assets	$ 705.0	$ 727.9
U.S.
Revenues from External Customers and Long-Lived Assets
Long-Lived Assets	184.4	199.2
Rest of North America
Revenues from External Customers and Long-Lived Assets
Long-Lived Assets	121.5	117.3
U.K.
Revenues from External Customers and Long-Lived Assets
Long-Lived Assets	31.8	32.6
Rest of EMEA
Revenues from External Customers and Long-Lived Assets
Long-Lived Assets	161.4	154.4
East Asia and India
Revenues from External Customers and Long-Lived Assets
Long-Lived Assets	54.9	65.6
Greater China
Revenues from External Customers and Long-Lived Assets
Long-Lived Assets	134.9	138.4
South America
Revenues from External Customers and Long-Lived Assets
Long-Lived Assets	$ 16.1	$ 20.4