The percentage of investment in reverse repurchase agreements which are collateralized by deposits.

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- Definition

Represents amount of transfers between fair value measurement levels.

+ References

No definition available.

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ 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)
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-Name Accounting Standards Codification
-Topic 320
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-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66010992&loc=d3e26610-111562

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No definition available.

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- Definition

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash
-URI http://asc.fasb.org/extlink&oid=6506951

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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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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Financial Instruments (Details) - USD ($) $ in Thousands	6 Months Ended
Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Financial Instruments
Transfers between fair value measurement levels	$ 0		$ 0
Cash and cash equivalents:
Cash and cash equivalents	29,369	$ 23,596	$ 24,278	$ 62,780
Available-for-sale securities:
Available-for-sale securities	$ 0	14,931
Corporate debt securities
Available-for-sale securities:
Available-for-sale securities		13,930
U.S. government-sponsored securities
Available-for-sale securities:
Available-for-sale securities		1,001
Government Securities and Obligations \| Reverse Repurchase Agreement \| Minimum
Financial Instruments
Percentage of investment amount to collateralized deposits value	102.00%
Recurring
Assets:
Total assets	$ 27,474	37,354
Recurring \| Money market funds
Cash and cash equivalents:
Cash and cash equivalents	17,466	22,423
Recurring \| Corporate debt securities
Cash and cash equivalents:
Cash and cash equivalents	4,008
Available-for-sale securities:
Available-for-sale securities		13,930
Recurring \| U.S. reverse repurchase agreements
Cash and cash equivalents:
Cash and cash equivalents	6,000
Recurring \| U.S. government-sponsored securities
Available-for-sale securities:
Available-for-sale securities		1,001
Recurring \| Level 1
Assets:
Total assets	17,466	22,423
Recurring \| Level 1 \| Money market funds
Cash and cash equivalents:
Cash and cash equivalents	17,466	22,423
Recurring \| Level 2
Assets:
Total assets	10,008	14,931
Recurring \| Level 2 \| Corporate debt securities
Cash and cash equivalents:
Cash and cash equivalents	4,008
Available-for-sale securities:
Available-for-sale securities		13,930
Recurring \| Level 2 \| U.S. reverse repurchase agreements
Cash and cash equivalents:
Cash and cash equivalents	$ 6,000
Recurring \| Level 2 \| U.S. government-sponsored securities
Available-for-sale securities:
Available-for-sale securities		$ 1,001