Supplemental Cash Flow and Noncash Investing Transactions (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)		Dec. 31, 2015 USD ($) Car	Dec. 31, 2014 USD ($) Car
Noncash or Part Noncash Divestitures [Line Items]
Capital Lease Obligations Incurred	$ 0.0		$ 17.8
Capital Leases, Future Minimum Payments Due, Next Twelve Months			$ 17.8	$ 0.0
Number of railcars received | Car			157	62
Capital Lease Obligations Incurred			14.8
Noncash or Part Noncash Acquisition, Value of Assets Acquired	0.0		$ 0.0	$ 1.1
Supplemental Cash Flow Information
Interest paid	145.4	[1]	144.4	142.6
Income taxes paid (refunded), net	28.6		13.3	18.7
Portfolio proceeds	$ 223.7		$ 482.2	$ 264.0

[1] (1) Interest paid consisted of interest on debt obligations, interest rate swaps (net of interest received), and capital leases. The interest expense we capitalized as part of the cost of construction of major assets was immaterial for all periods presented.