Concentrations of Credit Risk and Major Customers (Details) $ in Millions	12 Months Ended
Dec. 31, 2018 USD ($) Customer	Dec. 31, 2017 USD ($) Customer	Dec. 31, 2016
Concentration Risk
Concentration of risk, number of customers	5
Concentration Risk, Percentage	37.00%	38.00%	40.00%
Sales Revenue, Services, Net [Member] \| Customer Concentration Risk [Member]
Concentration Risk
Concentration of risk, number of customers	1	1
Concentration Risk, Percentage	12.50%	12.60%	12.30%
Baseline percentage for customer concentration of risk	10.00%	10.00%
Accounts Receivable [Member] \| Customer Concentration Risk [Member]
Concentration Risk
Accounts receivable \| $	$ 6.7	$ 7.5
Concentration Risk, Percentage	36.00%	32.00%

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

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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