Consolidated Statements of Cash Flows (unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Operating Activities:
Net loss	$ (28,329,000)	$ (30,644,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation of property and equipment	1,886,000	1,136,000
Amortization of intangible assets	164,000	155,000
Amortization of deferred financing costs	23,000	32,000
Change in fair value of warrant liability	(62,000)	527,000
Stock-based compensation	4,897,000	6,687,000
Other	(47,000)	111,000
Changes in assets and liabilities:
Accounts receivable, net	(31,978,000)	(20,167,000)
Prepaid expenses and other assets	133,000	(2,451,000)
Accounts payable and accrued liabilities	1,697,000	3,945,000
Deferred revenue	23,794,000	13,839,000
Deferred rent	(240,000)	379,000
Other liabilities	(330,000)	(261,000)
Net cash used in operating activities	(28,392,000)	(26,712,000)
Investing Activities:
Purchases of property and equipment	(3,410,000)	(3,139,000)
Purchases of intangible assets	(296,000)
Proceeds from disposal of property and equipment	18,000	18,000
Purchases of marketable securities		(1,153,000)
Maturities of marketable securities	325,000	500,000
Net cash used in investing activities	(3,363,000)	(3,774,000)
Financing Activities:
Proceeds from exercise of redeemable convertible preferred stock warrants		250,000
Proceeds from issuance of common stock from employee equity plans	3,311,000	111,000
Payments of line of credit financing costs		(32,000)
Repayment of capital lease obligations		(150,000)
Net cash provided by financing activities	3,311,000	179,000
Net decrease in cash and cash equivalents	(28,444,000)	(30,307,000)
Cash and cash equivalents, beginning of period	90,471,000	43,915,000
Cash and cash equivalents, end of period	62,027,000	13,608,000
Supplemental cash flow disclosure:
Cash paid for interest		11,000
Cash paid for taxes	31,000	44,000
Non-cash investing and financing activities:
Leasehold improvements		494,000
Capital expenditures incurred but not yet paid	54,000	642,000
Issuance of common stock for exercise of common stock warrant	244,000
Deemed dividends to investors		632,000
Vesting of common stock subject to repurchase	$ 7,000	$ 32,000