Segment information - Long lived assets by geography (Details) - USD ($) $ in Millions	Jan. 01, 2022	Jan. 02, 2021
Revenues from External Customers and Long-Lived Assets
Long-lived assets	$ 670.3	$ 705.0
U.S.
Revenues from External Customers and Long-Lived Assets
Long-lived assets	172.9	184.4
Rest of North America
Revenues from External Customers and Long-Lived Assets
Long-lived assets	127.1	121.5
U.K.
Revenues from External Customers and Long-Lived Assets
Long-lived assets	32.8	31.8
Rest of EMEA
Revenues from External Customers and Long-Lived Assets
Long-lived assets	151.3	161.4
East Asia and India
Revenues from External Customers and Long-Lived Assets
Long-lived assets	45.7	54.9
Greater China
Revenues from External Customers and Long-Lived Assets
Long-lived assets	124.8	134.9
South America
Revenues from External Customers and Long-Lived Assets
Long-lived assets	$ 15.7	$ 16.1