Retirement Benefits - Savings Plan (Details) - USD ($) $ in Millions		12 Months Ended
	Apr. 01, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Contribution Plan Disclosure [Line Items]
Matching defined contribution expense		$ 19.1	$ 11.9	$ 11.4
Defined contribution plan maximum annual contribution per employee percent	2.00%	2.00%
U.S. 401(K)
Defined Contribution Plan Disclosure [Line Items]
Matching defined contribution expense		$ 6.5	2.0	6.5
Other plans
Defined Contribution Plan Disclosure [Line Items]
Matching defined contribution expense		$ 12.6	$ 9.9	$ 4.9