Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net loss	$ (7,437)	$ (1,924)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	4,970	3,192
Amortization of operating lease right-of-use assets	1,394	1,010
Amortization of premium on marketable investments	177	(421)
Provision for doubtful accounts	255	14
Stock-based compensation	13,794	8,686
Gain on sale of convertible note held for investment	0	(217)
Amortization of debt discount and issuance costs	3,320	3,079
Others	147	(17)
Changes in operating assets and liabilities:
Accounts receivable	(2,620)	(1,046)
Prepaid expenses and other current assets	(2,754)	(1,721)
Deferred contract acquisition costs	(4,695)	(2,471)
Other assets	(2,132)	(7,845)
Accounts payable	(1,121)	552
Accrued and other current liabilities	4,802	7,724
Accrued federal fees and sales tax liability	(707)	(425)
Deferred revenue	3,378	416
Other liabilities	(377)	2,604
Net cash provided by operating activities	10,394	11,190
Cash flows from investing activities:
Purchases of marketable investments	(62,339)	(34,427)
Proceeds from maturities of marketable investments	134,610	39,497
Purchases of property and equipment	(6,045)	(3,985)
Cash paid to acquire substantially all of the assets of Whendu LLC	(100)	0
Proceeds from sale of convertible note held for investment	0	217
Net cash provided by investing activities	66,126	1,302
Cash flows from financing activities:
Proceeds from exercise of common stock options	2,596	982
Payments of finance leases	(1,229)	(1,894)
Net cash provided by (used in) financing activities	1,367	(912)
Net increase in cash and cash equivalents	77,887	11,580
Cash and cash equivalents:
Beginning of period	77,976	81,912
End of period	155,863	93,492
Supplemental disclosures of cash flow data:
Cash paid for interest	82	235
Cash paid for income taxes	109	42
Non-cash investing and financing activities:
Equipment purchased and unpaid at period-end	$ 2,280	$ 1,875