Leases - Summary of Maturities of Lease Liabilities Under Non-cancellable Leases (Details) $ in Millions	Mar. 31, 2019 USD ($)
Future Minimum Lease Payments - Operating Leases
2019	$ 4.7
2020	8.9
2021	9.0
2022	8.0
2023	6.2
Thereafter	23.5
Total undiscounted cash flows	60.3
Less imputed interest	(9.8)
Total lease liabilities	50.5
Future Minimum Lease Payments - Finance Leases
2019	11.8
2020	11.0
2021	9.2
2022	8.2
2023	1.0
Total undiscounted cash flows	41.2
Less imputed interest	(3.0)
Total lease liabilities	$ 38.2