Commitments and Contingencies Commitments and Contingencies, Leases - Components of Lease Expense (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Short-term Lease, Cost	$ 0.3
Operating Lease, Cost	27.8
Finance Lease, Right-of-Use Asset, Amortization	1.0
Finance Lease, Interest Expense	5.0
Finance Lease, Cost	6.0
PPAs
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	24.3
Other
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	$ 3.5