Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012		Jun. 30, 2011
Related Party Transaction [Line Items]
Contribution From Former Related Party			$ 156.4	[1]	$ (30.7)
Holdings [Member]
Related Party Transaction [Line Items]
Vessel management services expenses	(1.1)	(1.0)	(2.0)		(1.9)
Lease income from affiliate	1.0	1.2	2.1		2.1
Equipment and repair services income and other	0.9	0.6	1.4		1.2
Revenue from Related Parties	$ 0.8	$ 0.8	$ 1.5		$ 1.4

[1] Refer to Note 11, “Related Party Transactions.”