Summary of Significant Accounting Principles (Tables)

9 Months Ended

Sep. 30, 2017

Depreciable lives of property and equipment

Depreciation is computed using the straight-line method over the estimated useful lives of the related assets for financial statement purposes, as follows:



Automobiles and trucks	3 to 5 years
Buildings and improvements	5 to 30 years
Construction equipment	3 to 15 years
Vessels and other equipment	1 to 15 years
Office equipment	1 to 5 years

The following is a summary of property and equipment at September 30, 2017 and December 31, 2016:



	September 30, 2017			December 31, 2016
Automobiles and trucks	$	2,100		$	2,525
Building and improvements	37,928			37,269
Construction equipment	164,843			165,023
Vessels and other equipment	85,569			88,659
Office equipment	7,650			7,125
	298,090			300,601
Less: accumulated depreciation	(189,014		)	(181,293		)
Net book value of depreciable assets	109,076			119,308
Construction in progress	1,416			543
Land	38,287			38,231
	$	148,779		$	158,082