Equipment Acquisitions, Dispositions And Depreciation And Impairment Policies (Narrative) (Details) (USD $)	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Equipment Acquisitions, Dispositions And Depreciation And Impairment Policies [Line Items]
Capital expenditures	$ 212,428,000	$ 173,729,000
Net proceeds from equipment sold	50,573,000	172,993,000
Recognized gain on equipment sold	31,700,000
Currently recognized gain on equipment sold	25,100,000
Deferred gain on equipment sold	$ 6,600,000
Offshore Support Vessels [Member]
Equipment Acquisitions, Dispositions And Depreciation And Impairment Policies [Line Items]
Number of equipments delivered	3
Number of equipments sold	9
Inland River Dry Cargo Barges [Member]
Equipment Acquisitions, Dispositions And Depreciation And Impairment Policies [Line Items]
Number of equipments delivered	55
Liquid Tank Barges [Member]
Equipment Acquisitions, Dispositions And Depreciation And Impairment Policies [Line Items]
Number of equipments delivered	2
Helicopters [Member]
Equipment Acquisitions, Dispositions And Depreciation And Impairment Policies [Line Items]
Number of equipments delivered	9
Number of equipments sold	8
Harbor Tug [Member]
Equipment Acquisitions, Dispositions And Depreciation And Impairment Policies [Line Items]
Number of equipments delivered	1
Inland River Deck Barges [Member]
Equipment Acquisitions, Dispositions And Depreciation And Impairment Policies [Line Items]
Number of equipments sold	6
Inland River Towboat [Member]
Equipment Acquisitions, Dispositions And Depreciation And Impairment Policies [Line Items]
Number of equipments sold	1