SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Property and equipment

Depreciation of property and equipment is provided on the straight‑line method over the following estimated useful lives:

Vehicles	1 ‑ 5 years
Equipment	1 ‑ 20 years
Leasehold improvements	5 ‑ 20 years

Property and equipment consisted of the following at December 31, 2017 and 2016, respectively:

($ in thousands)	2017		2016
Equipment and vehicles	$	646,800	$	402,641
Leasehold improvements	4,987		4,500
Subtotal	651,787		407,141
Less accumulated depreciation	180,877		143,279
Property and equipment — net	$	470,910	$	263,862