Commitments and Contingencies Commitments and Contingencies, Leases - Right-of-Use Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Maximum lease term for short-term lease classification	12 months
Operating Lease, Right-of-Use Asset, Gross	$ 548.3
Operating Lease, Right-of-Use Asset, Accumulated Depreciation	(6.3)
Operating Lease, Right-of-Use Asset	542.0	$ 0.0
PPAs
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset, Gross	500.3
Other
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset, Gross	$ 48.0