Leases Leases - Supplemental balance sheet (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating lease assets	$ 292.2	$ 0.0
Finance lease assets	130.9
Total lease assets	423.1
Current liabilities operating leases	65.1
Current liabilities financing leases	25.6
Noncurrent liabilities operating leases	237.6	$ 0.0
Noncurrent liabilities financing leases	97.7
Total lease liabilities	$ 426.0