Maturities of Operating and Financing Lease Liabilities (Details) $ in Millions	Mar. 31, 2019 USD ($)
Operating Lease Liabilities, Payments Due [Abstract]
2019	$ 0.0
2020	0.0
2021	1.0
2022	0.0
2023	1.0
Remainder	6.0
Total lease payments	8.0
Less: Interest	(3.0)
Present value of lease liabilities	5.0
Operating lease, payments due, related to options to extend	2.0
Finance Lease Liabilities, Payments, Due [Abstract]
2019	3.0
2020	4.0
2021	4.0
2022	4.0
2023	4.0
Remainder	37.0
Total lease payments	56.0
Less: Interest	(30.0)
Present value of lease liabilities	26.0
Finance lease, liability, payments due, principal amount	26.0
Finance lease, liability, payments due, executory costs	9.0
Current finance lease liabilities	1.0
Operating And Finance Lease, Liabilities, Payments Due [Abstract]
2019	3.0
2020	4.0
2021	5.0
2022	4.0
2023	5.0
Remainder	43.0
Total lease payments	64.0
Less: Interest	(33.0)
Present value of lease liabilities	$ 31.0