Consolidated Statements of Cash Flows (unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating Activities:
Net loss	$ (40,646,000)	$ (40,856,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation of property and equipment	2,832,000	1,873,000
Amortization of intangible assets	284,000	232,000
Amortization of deferred financing costs	34,000	54,000
Change in fair value of warrant liability	(52,000)	536,000
Stock-based compensation	7,701,000	7,699,000
Other	120,000	165,000
Changes in assets and liabilities:
Accounts receivable, net	(13,887,000)	(3,229,000)
Prepaid expenses and other assets	849,000	(3,021,000)
Accounts payable and accrued liabilities	4,303,000	3,496,000
Deferred revenue	32,460,000	25,796,000
Deferred rent	(379,000)	504,000
Other liabilities	(361,000)	(285,000)
Net cash used in operating activities	(6,742,000)	(7,036,000)
Investing Activities:
Purchases of property and equipment	(4,922,000)	(4,463,000)
Purchases of intangible assets	(311,000)
Proceeds from disposal of property and equipment	23,000	53,000
Purchases of marketable securities	(24,363,000)	(1,456,000)
Maturities of marketable securities	325,000	500,000
Net cash used in investing activities	(29,248,000)	(5,366,000)
Financing Activities:
Proceeds from exercise of redeemable convertible preferred stock warrants		250,000
Proceeds from issuance of common stock from employee equity plans	4,494,000	246,000
Payments of line of credit financing costs		(32,000)
Repayment of capital lease obligations		(207,000)
Net cash provided by financing activities	4,494,000	257,000
Net decrease in cash and cash equivalents	(31,496,000)	(12,145,000)
Cash and cash equivalents, beginning of period	90,471,000	43,915,000
Cash and cash equivalents, end of period	58,975,000	31,770,000
Supplemental cash flow disclosure:
Cash paid for interest		18,000
Cash paid for taxes	49,000	67,000
Non-cash investing and financing activities:
Leasehold improvements		494,000
Capital expenditures incurred but not yet paid	210,000	164,000
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	$ 20,000	$ 40,000