Accounting for and Classification of Discontinued Operations: (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended				3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2012 CLX2 Service	Jun. 30, 2012 CLX2 Service	Jun. 30, 2013 CLX2 Service	Sep. 30, 2011 CLX2 Service item	Jul. 31, 2012 CLX2 Service Container and charter liabilities item	Sep. 30, 2011 CLX2 Service Other contractual liabilities item	Jun. 30, 2012 A&B	Jun. 30, 2012 A&B	Jun. 29, 2012 A&B
Accounting for and Classification of Discontinued Operations
Number of shares of common stock of A&B received for each share upon separation													1
Number of vessels used in discontinued operation								5
Number of vessels expected to be sub-chartered									2
Number of vessels returned to lessors										3
Duration of charter contracts										1 year
Future liability							$ 0
Income (losses) from discontinued operations
Income											72.4	116.4
Expenses					(2.2)	(4.4)					(78.9)	(119.8)
Tax benefit					0.8	1.6					0.4	0.1
Net loss from A&B											(6.1)	(3.3)
Loss from discontinued operations (net of tax)	$ 0	$ (7.5)	$ 0	$ (6.1)