Supplemental Cash Flow Information (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018
Cash:
Interest paid, net of capitalized interest	[1]	$ 228.4	$ 149.6
Income taxes paid, net of refunds		0.3	(0.5)
Non-cash investing activities:
Impact of capital expenditure accruals on property, plant and equipment		(150.9)	283.9
Transfers from materials and supplies inventory to property, plant and equipment		21.7	8.9
Non-cash financing activities:
Accrued distributions to noncontrolling interests		73.8
Non-cash balance sheet movements related to assets held for sale:
Working capital			12.6
Property, plant and equipment, net			$ 151.4
Lease liabilities arising from recognition of right-of-use assets:
Operating lease		6.7
Finance lease		$ 8.0

[1] Interest capitalized on major projects was $50.5 million and $30.8 million for the nine months ended September 30, 2019 and 2018.