CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net loss	$ (16,017)	$ (8,432)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	10,507	8,677
Stock-based compensation	16,035	15,822
Amortization of debt discount and issuance cost	4,883
Loss on disposal of property and equipment	34
Allowance (Recovery) for doubtful accounts	49	(497)
Deferred income taxes	302	173
Change in fair value of escrowed shares and contingent consideration, net	7,350	1,315
Changes in operating assets and liabilities:
Accounts receivable	(10,741)	2,097
Prepaid expenses and other current assets	(1,967)	(2,066)
Accounts payable and other current liabilities	(3,152)	(471)
Accrued compensation and benefits	(4,535)	(2,468)
Deferred revenues	1,109	1,119
Net cash provided by operating activities	3,857	15,269
Cash flows from investing activities:
Purchases of property and equipment	(2,327)	(3,166)
Purchase of intangible assets	(6,500)
Acquisitions, net of cash acquired	(20,947)	(21,048)
Purchases of short-term investments	(50,175)	(59,659)
Proceeds from maturities of short-term investment	59,902	94,250
Net cash provided by (used in) investing activities	(20,047)	10,377
Cash flows from financing activities:
Proceeds from issuances of common stock under stock plans	4,515	3,641
Payments for taxes related to net share settlement of equity awards	(8,240)
Repurchases of common stock	(6,734)
Principal payments on promissory note and capital lease obligations	(156)	(85)
Net cash provided by (used in) financing activities	(10,615)	3,556
Effect of exchange rates on cash and cash equivalents	6	18
Net increase (decrease) in cash and cash equivalents	(26,799)	29,220
Cash and cash equivalents at beginning of period	334,635	106,174
Cash and cash equivalents at end of period	307,836	135,394
Supplemental disclosures of cash flow information:
Cash paid for income taxes	87	59
Cash paid for interest	1,901
Supplemental disclosures of noncash investing and financing activities:
Fixed asset purchases not yet paid	$ 708	277
Computer equipment acquired under promissory note		819
Property and equipment acquired under capital lease		31
Crisp Acquisition
Supplemental disclosures of noncash investing and financing activities:
Issuance of shares related to Crisp acquisition		$ 12,957