Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating activities
Net income (loss)	$ 4,542	$ (3,545)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	6,224	5,434
Employee stock-based compensation	10,341	10,302
Write-off of previously capitalized software costs	2,347
Impairment of long-lived assets	2,095
Loss on disposal of property and equipment		35
Outside director restricted stock awarded in lieu of fees	100	100
Gain on sale of equity securities		(2,807)
Unrealized gain on revaluation of equity investment	(1,410)
Write-off of convertible promissory note	1,329
Deferred tax benefit from unrealized gain on available-for-sale marketable securities, net		820
Changes in assets and liabilities:
Accounts receivable	(3,698)	2,752
Prepaid expenses and other assets	(76)	1,397
Accounts payable	4,749	2,161
Accrued compensation and employee benefits	(3,203)	(6,545)
Accrued expenses and other liabilities	(1,099)	1,795
Net cash provided by operating activities	22,241	11,899
Investing activities
Purchases of property and equipment	(4,225)	(8,057)
Proceeds from sale of property and equipment		10
Purchases of marketable securities	(64,388)	(50,338)
Maturities of marketable securities	49,522	29,932
Proceeds from sales of marketable securities		10,155
Other investments	(2,500)
Net cash used in investing activities	(21,591)	(18,298)
Financing activities
Proceeds from issuance of common stock under stock plans	12,548	12,522
Withholding taxes related to restricted stock units net share settlement	(4,791)	(4,314)
Net cash provided by financing activities	7,757	8,208
Net increase in cash, cash equivalents and restricted cash	8,407	1,809
Cash, cash equivalents and restricted cash at the beginning of period	45,708	40,585
Cash, cash equivalents and restricted cash at the end of period	54,115	42,394
Non-cash investing and financing activities
Accrued purchases of property and equipment	747	$ 2,005
Change in fair value of equity investment	$ 81