Property and Equipment

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment Disclosure [Text Block]

6. Property and Equipment

Property and equipment consisted of the following at December 31: 

(dollars in thousands)	Estimated Useful Life in Years		2017			2016
Land		—	$	7,733		$	5,468
Buildings and improvements		3 to 39		22,718			21,660
Construction equipment		3 to 12		340,060			329,299
Office equipment		3 to 10		8,964			7,930
				379,475			364,357
Less: Accumulated depreciation and amortization				(231,391	)		(209,466	)
			$	148,084		$	154,891

Construction equipment includes assets under capital leases — see additional information provided in Note 12 — Lease Obligations to the Financial Statements.

Depreciation and amortization expense of property and equipment for the years ended December 31, 2017, 2016 and 2015 was $38.1 million, $38.2 million and $37.5 million, respectively.