Leases Leases - Financial Statement information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Operating lease assets	$ 41.0	$ 41.0	$ 0.0
Finance lease assets	1.0	1.0
Total lease assets	42.0	42.0
Operating lease liability, current	9.0	9.0
Finance lease liability, current	1.0	1.0
Operating Lease liability, noncurrent	33.0	33.0	$ 0.0
Finance lease liability, noncurrent	1.0	1.0
Total lease liabilities	42.0	42.0
Operating lease cost	3.0	7.0
Amortization of leased assets	0.0	0.0
Interest expense, net of capitalized interest	0.0	0.0
Total lease costs	$ 3.0	$ 8.0