Cash and Cash Equivalents, Restricted Cash and Marketable Securities (Details 1) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Cash and Cash Equivalents [Line Items]
Available-for-sale Securities, Amortized Cost	$ 20,291	$ 39,320
Available-for-sale Securities, Gross Unrealized Gains	17	21
Available-for-sale Securities, Gross Unrealized Losses	(8)	(13)
Available-for-sale Securities, Estimated Fair Value	20,300	39,328
Level 2 [Member] \| U.S. Treasury Notes [Member]
Cash and Cash Equivalents [Line Items]
Available-for-sale Securities, Amortized Cost	2,249	9,283
Available-for-sale Securities, Gross Unrealized Gains	0	7
Available-for-sale Securities, Gross Unrealized Losses	(3)	(2)
Available-for-sale Securities, Estimated Fair Value	2,246	9,288
Level 2 [Member] \| Fixed Income Debt Securities [Member]
Cash and Cash Equivalents [Line Items]
Available-for-sale Securities, Amortized Cost	18,042	30,037
Available-for-sale Securities, Gross Unrealized Gains	17	14
Available-for-sale Securities, Gross Unrealized Losses	(5)	(11)
Available-for-sale Securities, Estimated Fair Value	$ 18,054	$ 30,040

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Amount of investment in debt and equity securities categorized neither as trading securities nor held-to-maturity securities and intended be sold or mature one year or operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26626-111562

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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