Note 14 - Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2019

Notes Tables

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

March 31, 201 9	Total		Level 1		Level 2
Assets
Cash equivalents:
Money market funds	$	7,442	$	110	$	7,332
Commercial paper		123,448		—		123,448
Investment in marketable debt securities:
Municipal bonds		6,908		—		6,908
Corporate notes/bonds		146,321		—		146,321
Variable rate demand notes		8,900		—		8,900
Asset backed securities		30,627		—		30,627
Commercial paper		17,432		—		17,432
Certificate of deposit		818		818		—
	$	341,896	$	928	$	340,968

December 31, 201 8	Total		Level 1		Level 2
Assets
Cash equivalents:
Money market funds	$	740	$	38	$	702
Commercial paper		96,759		—		96,759
Investment in marketable securities:
Municipal bonds		6,733		—		6,733
Corporate notes/bonds		146,126		—		146,126
Variable rate demand notes		8,900		—		8,900
Asset-backed securities		32,923		—		32,923
Commercial paper		39,701		—		39,701
Certificate of deposit		956		956		—
	$	332,838	$	994	$	331,844