Note 4 - Fair Value - Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Mar. 31, 2016
Marketable equity securities		$ 1,771	$ 1,749
Auction rate preferred securities		350	350
Fair Value, Measurements, Recurring [Member]
Money market funds	[1],[2]	90,752	115,974
Marketable equity securities	[2],[3]	1,771	1,749
Auction rate preferred securities	[2],[3]	350	350
Total assets measured at fair value	[2]	92,873	118,073
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Money market funds	[1],[2]	90,752	115,974
Marketable equity securities	[2],[3]	1,771	1,749
Auction rate preferred securities	[2],[3]
Total assets measured at fair value	[2]	92,523	117,723
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Money market funds	[1],[2]
Marketable equity securities	[2],[3]
Auction rate preferred securities	[2],[3]	350	350
Total assets measured at fair value	[2]	$ 350	$ 350

[1] Included in "Cash and cash equivalents" on our audited consolidated balance sheets.

[2] We did not have any recurring fair value measurements of assets or liabilities whose fair value was measured using significant unobservable inputs.

[3] Included in "Other assets" on our audited consolidated balance sheets.