Revenue Recognition - Schedule of Cost and Estimated Earnings on Uncompleted Contracts (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Costs incurred on uncompleted contracts	$ 182,748	$ 169,544
Estimated earnings	94,802	90,737
Total	277,550	260,281
Less: Billings to date	254,840	240,665
Net under billings	$ 22,710	$ 19,616

Amounts due for billed services rendered or to be rendered, actions taken or to be taken, or a promise to refrain from taking certain actions in accordance with the terms of a legally binding agreement between the Company and, at a minimum, one other party. An example would be amounts billed to customers under contracts or programs but not paid as of the balance sheet date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3(c))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_BilledContractReceivables
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant