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Note 5 - Short-term Investments (Tables)

6 Months Ended

Jun. 30, 2018

Notes Tables

Debt Securities, Available-for-sale [Table Text Block]

		June 30, 2018
						Gross				Gross
		Amortized				Unrealized				Unrealized				Estimated
		Cost				Gains				Losses				Fair Value
U.S. treasury bills		$	39,768			$	3			$	—			$	39,771
U.S. corporate debt securities			19,176				—				(23	)			19,153
U.S. commercial paper			52,794				—				—				52,794
Foreign commercial paper			52,317				—				(5	)			52,312
Total		$	164,055			$	3			$	(28	)		$	164,030

		D ecember 31, 2017
						Gross				Gross
		Amortized				Unrealized				Unrealized				Estimated
		Cost				Gains				Losses				Fair Value
U.S. corporate debt securities		$	13,003			$	—			$	(10	)		$	12,993
U.S. commercial paper			4,929				—				—				4,929
Foreign commercial paper			9,874				—				—				9,874
Total		$	27,806			$	—			$	(10	)		$	27,796

X

- Definition

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-URI http://asc.fasb.org/topic&trid=2196928

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X

- References

No definition available.

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