Inventories (Tables)

6 Months Ended

Jun. 30, 2017

Inventory Disclosure [Abstract]

Inventories

	June 30, 2017			December 31, 2016
	(in thousands)
Raw materials	$	55,930		$	43,438
Work in process	2,867			2,279
Finished goods	5,920			3,017
	64,717			48,734
Less:  Allowance for excess and obsolete inventories	(1,642		)	(1,382		)
Total, net	$	63,075		$	47,352

Inventories (Allowance)

The related changes in the allowance for excess and obsolete inventories account are as follows:

	Three months ended				Six months ended
	June 30, 2017		June 30, 2016		June 30, 2017		June 30, 2016
Allowance for excess and obsolete inventories:	(in thousands)
Balance, beginning of period	$	1,442	$	894	$	1,382	$	757
Provisions for excess and obsolete inventories	200		171		260		308
Inventories written off	—		—		—		—
Balance, end of period	$	1,642	$	1,065	$	1,642	$	1,065