Business and Basis of Presentation (Details) $ in Thousands		3 Months Ended		9 Months Ended
	Oct. 21, 2015 segment	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) segment	Sep. 30, 2014 USD ($)
Number of operating segments | segment				6
Long-term debt reclassified to current		$ 213,700		$ 213,700
Minimum percentage of ownership considered for consolidation (in hundredths)				50.00%
Minimum percentage of ownership considered for equity method of accounting for investments (in hundredths)				20.00%
Maximum percentage of ownership considered for equity method of accounting for investments (in hundredths)				50.00%
Amortization expense for deferred charges - drydock			$ 5,100		$ 13,700
Miscellaneous depreciation expense		$ 185	$ 181	$ 556	$ 545
Subsequent Event [Member]
Number of operating segments | segment	3