Accounts Receivable, Net - Accounts Receivable due to contract changes, negotiated settlements and claims for unanticipated cost (Details) - USD ($) $ in Thousands	Jun. 28, 2019	Dec. 31, 2018
Accounts Receivable, Net [Abstract]
Contract changes, negotiated settlements and claims for unanticipated contract costs	$ 900	$ 900

Amount of billed or unbilled claims or other similar items subject to uncertainty concerning their determination or ultimate realization under long-term contracts.

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)(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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