Acquisitions And Dispositions (Narrative) (Details) (USD $)	12 Months Ended																	12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended					12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Offshore Support Vessels Anchor Handling Towing Supply [Member]	Dec. 31, 2011 Offshore Support Vessels Anchor Handling Towing Supply [Member]	Dec. 31, 2013 Liftboats [Member]	Dec. 31, 2011 Offshore Support Vessels [Member]	Dec. 31, 2013 Inland River Liquid Tank Barges [Member]	Dec. 31, 2013 Harbor Tugs [Member]	Dec. 31, 2012 Harbor Tugs [Member]	Dec. 31, 2013 Minimum [Member]	Dec. 31, 2012 Minimum [Member]	Dec. 31, 2013 Maximum [Member]	Dec. 31, 2012 Maximum [Member]	Dec. 31, 2013 C-Lift LLC [Member]	Jun. 06, 2013 C-Lift LLC [Member]	Jun. 06, 2013 C-Lift LLC [Member] Liftboats [Member]	Dec. 31, 2012 Pantagro Acquisition [Member]	Jun. 25, 2012 Pantagro Acquisition [Member]	Dec. 31, 2012 Superior Liftboats [Member]	Mar. 30, 2012 Superior Liftboats [Member] Liftboats [Member]	Dec. 31, 2012 ICP Acquisition [Member]	Feb. 01, 2012 ICP Acquisition [Member]	Dec. 31, 2011 Lewis & Clark Acquisition [Member]	Dec. 31, 2012 Windcat Acquisition [Member]	Dec. 31, 2011 Windcat Acquisition [Member]	Dec. 22, 2011 Windcat Acquisition [Member]	Dec. 22, 2011 Windcat Acquisition [Member] Wind Farm Utility Vessel [Member] equipment	Dec. 31, 2011 Naviera Acquisition [Member]	Dec. 21, 2011 Naviera Acquisition [Member]	Dec. 31, 2011 Soylutions Acquisition [Member]	Jul. 29, 2011 Soylutions Acquisition [Member]	Dec. 31, 2011 G & G Shipping Acquisition [Member]	Apr. 13, 2011 G & G Shipping Acquisition [Member] R O R O Vessels [Member] equipment	Dec. 31, 2011 PIER Acquisition [Member]	Dec. 01, 2009 PIER Acquisition [Member]	Dec. 31, 2012 Offshore Marine Services Joint Ventures [Member]	Dec. 31, 2011 Offshore Marine Services Joint Ventures [Member]	Dec. 31, 2012 Offshore Marine Services Joint Ventures [Member] Offshore Support Vessels [Member]	Dec. 31, 2011 Offshore Marine Services Joint Ventures [Member] Offshore Support Vessels [Member]	Dec. 31, 2011 Common Stock [Member] Windcat Acquisition [Member]	Dec. 31, 2013 Gains on Asset Dispositions and Impariments, Net [Member]	Dec. 31, 2012 Gains on Asset Dispositions and Impariments, Net [Member]	Dec. 31, 2011 Gains on Asset Dispositions and Impariments, Net [Member]
Business Acquisition [Line Items]
Controlling interest obtained																50.00%			95.00%				70.00%				75.00%			70.00%		100.00%
Cash paid on acquisition															$ 13,300,000			$ 200,000		$ 142,500,000		$ 9,100,000		$ 29,600,000		$ 21,500,000			$ 1,900,000		$ 11,900,000		$ 30,300,000
Number Of Equipments Acquired																	2				18							29						8
Business Combination, Consideration Transferred																		400,000								22,100,000							33,500,000
Purchase consideration, note receivable																		200,000															3,200,000
Business Acquisition, Cost of Acquired Entity, Equity Interests Issued and Issuable																									600,000													1,200,000			6,374
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01	$ 0.01
Goodwill, Acquired During Period																													1,000,000				600,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High																																				1,300,000
Maximum additional consideration received by selling partner																																				700,000
Business Acquisition, Additional Consideration Paid to Acquired Entity																																			600,000
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability																																			100,000
Business acquisition additional consideration earned by acquired entity																																			800,000
Sales Price Of Equipment	274,300,000	167,500,000	81,800,000
Proceeds from Sale of Property, Plant and Equipment, Excluding Deposits on Future Equipment Sales	263,900,000	114,000,000	70,700,000
Proceeds from Issuance of Secured Debt	10,400,000	48,500,000	7,400,000																																		48,900,000	7,600,000
Gain (Loss) on Disposition of Property Plant Equipment	64,500,000	36,200,000	27,500,000																																								500,000
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property																																										37,600,000	13,000,000	15,200,000
Deferred gains on asset sales	26,900,000	23,200,000	12,300,000																																				7,300,000	4,600,000
Sale Leaseback Transaction, Description of Asset(s)				2	1	1		8	7	2
Sale Leaseback Transaction, Net Proceeds	116,300,000	84,500,000	36,300,000
Sale Leaseback Transaction, Lease Terms			84								60	48	120	96
Sale Leaseback Transaction, Deferred Gain, Net	26,400,000	15,700,000	7,700,000
Amortization Of Deferred Gains Included In Gains On Asset Dispositions And Impairments, Net																																										2,900,000	12,200,000	3,700,000
Payments for (Proceeds from) Other Deposits		$ 5,000,000	$ 2,500,000				$ 5,000,000
Property, Plant and Equipment, Dispositions																																							2	1