Equipment Acquisitions, Dispositions And Depreciation And Impairment Policies (Tables)

9 Months Ended

Sep. 30, 2011

Equipment Acquisitions, Dispositions And Depreciation And Impairment Policies [Abstract]

Deferred Gain Activity

	2011			2010
Balance at beginning of period	$	131,836		$	93,231
Deferred gains arising from asset sales		6,587			8,530
Amortization of deferred gains included in operating expenses as a reduction to rental expense		(16,773	)		(12,440	)
Amortization of deferred gains included in gains on asset dispositions and impairments, net		(3,407	)		(20,626	)
Balance at end of period	$	118,243		$	68,695

Estimated Useful Life Of Equipment

Offshore support vessels	20
Helicopters(1)	15
Inland river dry cargo and deck barges	20
Inland river liquid tank barges	25
Inland river towboats	25
U.S.-flag tankers(2)	25
RORO vessels	20
Harbor and offshore tugs	25
Ocean liquid tank barges	25

(1) Effective July 1, 2011, the Company changed its estimated useful life and salvage value for helicopters from 12 to 15 years and 30% to 40%, respectively, due to improvements in new aircraft models that continue to increase their long-term value and make them viable for operation over a longer period of time. For the three and nine months ended September 30, 2011, the change in estimate increased operating income by $3.7 million, net income by $2.4 million and basic and diluted earnings per share by $0.11.

(2) Subject to Oil Pollution Act of 1990 ("OPA 90") requirements.