Leases Leases - Supplemental balance sheet (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Leases [Abstract]
Operating lease assets	$ 280.8	$ 0.0
Finance lease assets	145.9
Total lease assets	426.7
Current liabilities operating leases	61.7
Current liabilities financing leases	29.0
Noncurrent liabilities operating leases	229.9	$ 0.0
Noncurrent liabilities financing leases	104.7
Total lease liabilities	$ 425.3