Leases Maturities of Operating Lease Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Leases [Abstract]
2019 (remaining nine months)	$ 9.6
2020	11.5
2021	9.8
2022	8.1
2023	7.6
Thereafter	49.0
Operating leases liabilities payments due	95.6
Less: imputed lease interest	18.0
Total lease liabilities	$ 77.6
2019		$ 13.0
2020		10.5
2021		7.8
2022		6.9
2023		5.5
Thereafter		37.8
Total		$ 81.5