Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Commitments and Contingencies (Textual) [Abstract]
Period for Lease Renewal	2 years
Interest of Subsidiary in Lease Assets Owned Entity	5.00%
Vessel's gross asset value under the capital lease at inception	$ 37.6
Vessel's gross asset value under the capital lease at depreciation	13.2		12.2
Other long-term liabilities	28.6	29.5
Accounts Payable Related to Obligations Under Capital Lease	3.6
2012	2.7
2013	3.9
2014	4.2
2015	4.6
2016	5.0
2017	5.4
Capital Leases of Lessee Variable Rate of Interest	8.50%
Interest Expense	$ 0.7	$ 0.8