Summary of Significant Accounting Policies - Maturities of Lease Liabilities, Topic 842 (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Finance Leases
2019	$ 0.5
2020	2.0
2021	2.0
2022	1.4
2023	0.2
Thereafter	0.1
Total lease payments	6.2
Less imputed interest	0.5
Total	5.7	$ 5.8
Operating Leases
2019	20.6
2020	70.1
2021	31.5
2022	18.9
2023	11.6
Thereafter	16.1
Total lease payments	168.8
Less imputed interest	15.8
Total	$ 153.0