Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income	$ 6,945	$ 7,602
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	2,212	2,170
Deferred income taxes	(168)	412
Stock-based compensation	491	405
Impairment of investment	345	0
Net change in accrued interest, premiums, and discounts on investments	5	(98)
Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities	9,830	10,491
Changes in operating assets and liabilities:
Accounts receivable	(5,097)	(4,445)
Inventories	(697)	1,275
Prepaid expenses	1,562	3,320
Other non-current assets	(62)	(166)
Accounts payable and accrued liabilities	(487)	(3,280)
Accrued income and other taxes	2,209	454
Other non-current liabilities	(120)	96
Net Cash Provided by (Used in) Operating Activities, Continuing Operations, Total	7,138	7,745
Cash flows from investing activities:
Property, plant and equipment additions	(2,947)	(2,661)
Purchase of investments	(1,676)	0
Proceeds from maturities of investments	0	8,400
Net Cash Provided by (Used in) Investing Activities, Continuing Operations, Total	(4,623)	5,739
Cash flows from financing activities:
Purchase of treasury stock	(1,276)	(16,985)
Dividends paid	(1,638)	(1,403)
Net Cash Provided by (Used in) Financing Activities, Continuing Operations, Total	(2,914)	(18,388)
Net change in cash and cash equivalents	(399)	(4,904)
Cash and cash equivalents at beginning of period	28,346	20,775
Cash and cash equivalents at end of period	27,947	28,346
Cash paid for:
Income taxes	$ 104	$ 87