Commitments and Contingencies - Schedule of Future Minimum Contracts of Affreightment and Royalty Commitments for All Noncancelable Agreements (Detail) $ in Millions	Dec. 31, 2020 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2021	$ 16.4
2022	16.6
2023	16.9
2024	17.2
2025	17.4
Thereafter	35.7
Total	120.2
2021	18.0
2022	11.3
2023	10.4
2024	9.4
2025	8.9
Thereafter	61.7
Total	$ 119.7