Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Supplemental Cash Flow Information [Abstract]
Cash (paid) for interest, net of amount capitalized	$ (116.2)	$ (116.2)	$ (117.9)
Cash (paid) for income taxes, net		(58.5)	(20.8)
Cash received for income taxes	100.2
Accounts payable related to construction costs	$ 9.1	$ 11.7	$ 1.7