Accounts Payable and Accrued Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Components of accounts payable and accrued liabilities [Abstract]
Commodities	$ 574.4	$ 378.5
Other goods and services	117.0	142.9
Interest	52.3	81.0
Compensation and benefits	37.2	16.0
Income and other taxes	24.2	13.4
Preferred dividends payable	22.9
Other	15.5	18.6
Accounts payable and accrued liabilities	$ 843.5	$ 650.4