Summary of Significant Accounting Policies - Classification of Recoverable Customer Engineering, Development and Tooling Costs related to Long-Term Supply Agreements (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Pre Production Costs Related to Long Term Supply Arrangements [Line Items]
Recoverable customer E&D and tooling	$ 333.4	$ 271.0
Current
Pre Production Costs Related to Long Term Supply Arrangements [Line Items]
Recoverable customer E&D and tooling	212.0	157.2
Long-term
Pre Production Costs Related to Long Term Supply Arrangements [Line Items]
Recoverable customer E&D and tooling	$ 121.4	$ 113.8