Employee Benefits - Additional Information (Details) $ in Millions	Mar. 31, 2021 USD ($)
U.K.
Defined Benefit Plan Disclosure [Line Items]
Expected future employer cash contribution	$ 8
Other
Defined Benefit Plan Disclosure [Line Items]
Expected future employer cash contribution	19
U.S.
Defined Benefit Plan Disclosure [Line Items]
Expected future employer cash contribution	$ 73