Leases - Maturity (Details) $ in Millions	Mar. 31, 2019 USD ($)
Undiscounted finance lease liability
Total	$ 0.8
2019 (remaining)	0.8
2020	0.0
2021	0.0
2022	0.0
2023	0.0
Thereafter	0.0
Reduction due to present value
Total	0.0
2019 (remaining)	0.0
2020	0.0
2021	0.0
2022	0.0
2023	0.0
Thereafter	0.0
Finance lease liability
Total	0.8
2019 (remaining)	0.8
2020	0.0
2021	0.0
2022	0.0
2023	0.0
Thereafter	0.0
Undiscounted operating lease liability
Total	139.2
2019 (remaining)	16.5
2020	16.0
2021	12.9
2022	9.1
2023	8.9
Thereafter	75.8
Reduction due to present value
Total	(41.0)
2019 (remaining)	(3.6)
2020	(4.2)
2021	(3.7)
2022	(3.4)
2023	(3.0)
Thereafter	(23.1)
Operating Lease Liability [Abstract]
Total	98.2
2019 (remaining)	12.9
2020	11.8
2021	9.2
2022	5.7
2023	5.9
Thereafter	52.7
Total lease liability, Total	99.0
Total lease liability, 2019 (remaining)	13.7
Total lease liability, 2020	11.8
Total lease liability, 2021	9.2
Total lease liability, 2022	5.7
Total lease liability, 2023	5.9
Total lease liability, Thereafter	$ 52.7