Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net income (loss)	$ (39,381)	$ 2,858	$ 4,123
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization of property and equipment	904	996	500
Amortization of intangibles	6	20	67
Stock-based compensation	6,111	5,470	5,295
Deferred income taxes	24,274	9,935	1,893
Allowance for doubtful accounts	2	(6)	16
Loss on disposal of equipment	17	10	52
Income from discontinued operations	(649)	0	0
Changes in operating assets and liabilities:
Accounts and other receivables	(171)	1,814	(2,439)
Prepaid income taxes	1,998	(6,995)	0
Prepaid expenses and other current assets	(86)	(1,945)	(155)
Intangibles and other assets	(275)	(36)	(39)
Accounts payable	5,322	(19)	(10)
Accrued compensation and other current liabilities	967	3,750	(2,241)
Deferred revenue	23,090	(6,394)	(6,755)
Other long-term liabilities	(87)	587	(16)
Net cash provided by operating activities	22,042	10,045	291
Cash flows provided by (used in) investing activities:
Purchases of short-term investments	(32,813)	(44,910)	(42,953)
Proceeds from maturities of short-term investments	40,000	48,000	57,000
Purchases of property and equipment	(343)	(4,430)	(779)
Proceeds from discontinued operations	1,000	0	0
Net cash provided by (used in) investing activities	7,844	(1,340)	13,268
Cash flows provided by (used in) financing activities:
Issuance of common stock under employee stock purchase plan	307	367	381
Exercise of stock options, net of shares withheld for employee taxes	2,388	1,561	1,304
Purchases of treasury stock	(729)	0	(15,000)
Net cash provided by (used in) financing activities	1,966	1,928	(13,315)
Net increase in cash and cash equivalents	31,852	10,633	244
Cash and cash equivalents:
Beginning of year	25,013	14,380	14,136
End of year	56,865	25,013	14,380
Supplemental disclosure of cash flow information:
Cash paid for taxes	(419)	156	47
Supplemental disclosure of noncash operating, investing, and financing activities:
Amounts accrued for property and equipment	22	18	60
Cashless option exercise under company stock plan	177	69	0
Release of Restricted Stock Units and Awards under company stock plan	$ 2,257	$ 3,059	$ 3,976