Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Supplemental Cash Flow Information [Abstract]
Cash paid for interest, net of amount capitalized	$ 60.6	$ 65.6
Cash paid for income taxes, net of refunds	58.7	15.7
Accounts payable related to construction costs	$ 5.0	$ 4.8