Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net loss	$ (13,161)	$ (10,718)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation, amortization and write-off of property and equipment	664	688
Amortization and write-off of intangibles	486	639
Stock-based compensation	3,093	2,707
Changes in operating assets and liabilities:
Trade accounts receivable	1,181	2,139
Other current assets	(163)	52
Other assets	50	36
Accounts payable and other accrued liabilities	336	109
Deferred revenue	(835)	(917)
Net cash used in operating activities	(8,349)	(5,265)
Cash flows from investing activities:
Purchase of property and equipment	(938)	(755)
Capitalized patent costs	(406)	(436)
Maturity of marketable securities	28,636	22,467
Purchase of marketable securities	(13,261)	(8,819)
Net cash provided by investing activities	14,031	12,457
Cash flows from financing activities:
Issuance of common stock, net of issuance costs	17,702	0
Exercise of stock options	568	309
Purchase of common stock	(1,348)	(1,104)
Net cash provided by (used) in financing activities	16,922	(795)
Net increase in cash and cash equivalents	22,604	6,397
Cash and cash equivalents at beginning of period	11,638	3,160
Cash and cash equivalents at end of period	34,242	9,557
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net	25	14
Supplemental schedule of non-cash investing activities:
Property and equipment and patent costs in accounts payable	(22)	61
Stock-based compensation capitalized to software and patent costs	$ 98	$ 75