Marketable Securities - Available-for-Sale (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Marketable Securities, Current [Abstract] (Deprecated 2018-01-31)
Amortized cost basis, current	$ 460	$ 401
Accumulated gross unrealized gains, current	6,662	11,394
Accumulated gross unrealized losses, current	0	0
Fair value, current	7,122	11,795
Mortgage securities
Marketable Securities, Current [Abstract] (Deprecated 2018-01-31)
Amortized cost basis, current	458	400
Accumulated gross unrealized gains, current	6,662	11,394
Accumulated gross unrealized losses, current	0	0
Fair value, current	7,120	11,794
Equity securities
Marketable Securities, Current [Abstract] (Deprecated 2018-01-31)
Amortized cost basis, current	2	1
Accumulated gross unrealized gains, current	0	0
Accumulated gross unrealized losses, current	0	0
Fair value, current	$ 2	$ 1

Debt Securities, Available-for-sale Securities, Current, Accumulated Gross Unrealized Gains

No definition available.

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- Definition

Debt Securities, Available-for-sale Securities, Current, Accumulated Gross Unrealized Losses

+ References

No definition available.

+ Details

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- Definition

Debt Securities, Available-for-sale Securities, Current, Amortized Cost Basis

+ References

No definition available.

+ Details

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- References

No definition available.

+ Details

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- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26626-111562

+ Details

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- Details

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- Details

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