For an unclassified balance sheet, the amount due from customers or clients for goods or services that have been delivered or sold in the normal course of business, reduced to their estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(9))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: 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))
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Reference 3: 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(4))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(5))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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Period Type:	instant

Segments - Schedule of Activities with Major Customers (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) customer	Dec. 31, 2017 USD ($)	Dec. 31, 2016
Segment Reporting [Abstract]
Number of major customers \| customer	2
Panasonic \| Customer Concentration Risk \| Consolidated Revenue
Revenue, Major Customer
Percent of consolidated revenue	14.40%	19.10%	21.60%
Panasonic \| Customer Concentration Risk \| Accounts Receivable
Revenue, Major Customer
Accounts receivable	$ 14,994	$ 10,200
Boeing \| Customer Concentration Risk \| Consolidated Revenue
Revenue, Major Customer
Percent of consolidated revenue	14.30%	16.80%	15.20%
Boeing \| Customer Concentration Risk \| Accounts Receivable
Revenue, Major Customer
Accounts receivable	$ 24,649	$ 12,969