Revenue from Contracts with Customers (ASC 606) Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 43,517	$ 127,010
Mobile Connectivity [Member] \| Connectivity Product [Member] \| Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	6,297	19,698
Mobile Connectivity [Member] \| Connectivity Product [Member] \| Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,259	3,881
Mobile Connectivity [Member] \| Connectivity Service [Member]
Disaggregation of Revenue [Line Items]
Revenues	25,869	76,359
Intertial Navigation [Member] \| Navigation Product [Member]
Disaggregation of Revenue [Line Items]
Revenues	8,811	22,942
Intertial Navigation [Member] \| Navigation Service [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 1,281	$ 4,130

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 32
-Paragraph 2A
-URI http://asc.fasb.org/extlink&oid=82859839&loc=SL82860478-203043

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130543-203045

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130539-203045

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130545-203045

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration