Dispositions (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2015	Mar. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Purchase price of leased vessels		$ 67.4
Amount of notes receivable net	$ 115.0
Impairment Of Long Lived Assets To Be Disposed Of	$ 15.5
Ullswater Vessel [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Repayments of Long-term Capital Lease Obligations		$ 20.9