Supplemental Cash Flow Information (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019
Cash:
Interest paid, net of capitalized interest	[1]	$ 171.8	$ 113.2
Income taxes (received), net of payments		(44.4)	0.4
Non-cash investing activities:
Transfers from materials and supplies inventory to property, plant and equipment		1.8	16.4
Non-cash financing activities:
Changes in accrued distributions to noncontrolling interests		(1.9)	49.6
Retained Earnings [Member]
Non-cash investing activities:
Impact of capital expenditure accruals on property, plant and equipment, net		$ (143.9)	$ (4.8)

[1] Interest capitalized on major projects was $22.5 million and $36.1 million for the six months ended June 30, 2020 and 2019.