Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash flows from operating activities:
Net loss	$ (12,631)	$ (6,651)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation, amortization and write-off of property and equipment	930	708
Amortization and write-off of intangibles	794	916
Changes in allowance for doubtful accounts	16	(13)
Stock-based compensation	3,857	4,085
Deferred income taxes		(2,874)
Changes in operating assets and liabilities:
Trade accounts receivable	1,842	2,000
Other current assets	(251)	(1,559)
Other assets	66	160
Accounts payable and other accrued liabilities	280	(340)
Deferred revenue	(1,929)	(2,338)
Net cash used in operating activities	(7,026)	(5,906)
Cash flows from investing activities:
Purchase of property and equipment	(747)	(1,010)
Capitalized patent costs	(646)	(922)
Maturity of marketable securities	79,985	47,961
Purchase of marketable securities	(78,620)	(38,840)
Net cash provided by (used in) investing activities	(28)	7,189
Cash flows from financing activities:
Issuance of common stock, net of issuance costs	12,896	(124)
Exercise of stock options	1,321	1,319
Purchase of common stock	(1,833)	(1,931)
Cash dividends paid		(1,654)
Net cash provided by (used in) financing activities	12,384	(2,390)
Net increase (decrease) in cash and cash equivalents	5,330	(1,107)
Cash and cash equivalents at beginning of period	6,122	3,811
Cash and cash equivalents at end of period	11,452	2,704
Supplemental disclosure of cash flow information:
Cash paid (received) for income taxes, net	22	(12)
Supplemental schedule of non-cash investing activities:
Property and equipment and patent costs included in accounts payable	73	194
Stock-based compensation capitalized to patent costs and software	$ 137	$ 133