Supplemental Cash Flow and Noncash Investing Transactions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 Vessel		Dec. 31, 2012	Dec. 31, 2011
Noncash or Part Noncash Divestitures [Line Items]
Number of vessels received	5
Noncash or Part Noncash Acquisition, Value of Assets Acquired	$ 174.7		$ 0
Fair Value of Assets Acquired	22.9			88.8
Supplemental Cash Flow Information
Interest paid	148.7	[1]	162.3	152.7
Income taxes paid (refunded), net	7.4		11.1	(2.8)
Portfolio proceeds	$ 385.3		$ 288.9	$ 154.1

[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.