Note 5 - Fair Value Measurements

3 Months Ended

Mar. 31, 2019

Notes to Financial Statements

Fair Value Disclosures [Text Block]

5. Fair Value Measurements

The Company’s investments are all classified within Level

1

of the fair value hierarchy and are valued based on quoted prices in active markets. For cash and cash equivalents, current receivables, accounts payable, and interest accrual, the carrying amounts approximate fair value because of the short maturity of these instruments, and therefore fair value information is

not

included in the table below. 

The fair value hierarchy of the Company's cash equivalents and investments at fair value was as follows:

			Fair Value Measurements at Reporting Date Using
	March 31, 2019		Quoted Prices in Active Markets  for Identical Assets   (Level 1)		Significant Other  Observable Inputs   (Level 2)		Significant   Unobservable Inputs   (Level 3)		Amortized Cost
Cash equivalents:
Money market funds	$	2,147	$	2,147	$	–	$	–	$	2,147
Investments:
U.S. treasury bills	$	71,221	$	71,221	$	–	$	–	$	71,221

			Fair Value Measurements at Reporting Date Using
	December 31, 2018		Quoted Prices in Active Markets  for Identical Assets   (Level 1)		Significant Other  Observable Inputs   (Level 2)		Significant   Unobservable Inputs   (Level 3)		Amortized Cost
Cash equivalents:
Money market funds	$	4,984	$	4,984	$	–	$	–	$	4,984
Investments:
U.S. treasury bills	$	69,972	$	69,972	$	–	$	–	$	69,972