Revenue (Tables)

3 Months Ended

Mar. 31, 2019

Revenue from Contract with Customer [Abstract]

Contract with Customer, Asset and Liability

The following table presents the beginning and ending balances and significant changes in the costs in excess of billings and billings in excess of cost balance during the three months ended March 31, 2019 and 2018, respectively (in thousands):

	March 31, 2019			December 31, 2018
Costs in excess of billings	$	25,519		$	22,634
Billings in excess of cost	(18,259		)	(17,857		)
Unearned revenue	(12,917		)	(12,028		)

	Three Months Ended March 31, 2019		Three Months Ended March 31, 2018
Revenue recognized in the period from:
Amounts included in billings in excess of cost  at the beginning of the period	$	9,697	$	8,340
Amounts included in unearned revenue  at the beginning of the period	$	4,661	$	1,836