Segments - Assets by Reportable Segments (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Assets not allocated:
Cash and cash equivalents	$ 393.7	$ 548.7	$ 262.4
Current assets held for sale	3.3	0.3
Income tax receivables	31.4	71.2
Other receivables	96.7	69.5
Deferred taxes	172.1	187.1
Other	368.6	355.8
Total assets	6,159.8	6,083.8
Assets allocated to segments:
Assets allocated to segments:
Assets allocated to segments	5,053.7	4,814.5
Assets allocated to segments: | Food
Assets allocated to segments:
Assets allocated to segments	2,168.2	2,019.1
Assets allocated to segments: | Protective
Assets allocated to segments:
Assets allocated to segments	2,885.5	2,795.4
Assets not allocated:
Assets not allocated:
Cash and cash equivalents	393.7	548.7
Current assets held for sale	3.3	0.3
Income tax receivables	31.4	71.2
Other receivables	96.7	69.5
Deferred taxes	172.1	187.1
Other	408.9	392.5
Total assets	$ 6,159.8	$ 6,083.8