Note 5 - Balance Sheet Components - Other Current Assets (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017
Prepaid wafer purchase	[1]		$ 6,217
Prepaid wafer refund receivable		4,297		[1]
Other prepaid expense		3,425	2,742
Assets for product returns	[2]	1,602
Interest receivable		1,441	1,352
Value-added tax receivable		423	1,235
Other		743	1,216
Total		$ 11,931	$ 12,762

[1] In December 2018, a supplier terminated a prepaid wafer purchase agreement with the Company and agreed to refund the Company the remaining wafer purchase prepayment of $4.3 million, which was recorded as a receivable as of December 31, 2018.

[2] Under Topic 606, "assets for product returns" primarily represent the carrying value of inventory the Company expects to recover from customers related to stock rotation returns. Prior to the adoption of Topic 606, such amounts were netted against the stock rotation reserve within current accrued liabilities.