Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net loss	$ (22,924)	$ (11,673)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	4,843	3,427
Amortization of debt discount and issuance costs	2,743	2,510
Stock-based compensation expense	13,347	8,634
Provision for doubtful accounts	527	437
Foreign currency re-measurement loss	447	249
Other non-cash (income) expense	(138)	(722)
Changes in operating assets and liabilities:
Accounts receivable	22,608	14,729
Deferred contract acquisition and fulfillment costs	(516)	(1,094)
Prepaid expenses and other assets	135	(5,940)
Accounts payable	4,010	66
Accrued expenses	(14,563)	(13,690)
Deferred revenue	(16,671)	(12,104)
Other liabilities	(1,063)	1,605
Net cash used in operating activities	(7,215)	(13,566)
Cash flows from investing activities:
Purchases of property and equipment	(2,756)	(8,463)
Capitalization of internal-use software costs	(1,474)	(1,601)
Purchases of investments	(24,272)	(63,029)
Sales/maturities of investments	113,924	72,738
Net cash provided by (used in) investing activities	85,422	(355)
Cash flows from financing activities:
Taxes paid related to net share settlement of equity awards	(1,533)	(979)
Proceeds from employee stock purchase plan	3,346	2,634
Proceeds from stock option exercises	1,561	2,718
Net cash provided by financing activities	3,374	4,373
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(560)	(148)
Net increase (decrease) in cash, cash equivalents and restricted cash	81,021	(9,696)
Cash, cash equivalents and restricted cash, beginning of period	123,413	99,565
Cash, cash equivalents and restricted cash, end of period	204,434	89,869
Supplemental cash flow information:
Cash paid for interest on convertible senior notes	1,438	1,342
Cash paid for income taxes, net of refunds	33	88
Non-cash investing activities:
Leasehold improvements acquired through tenant improvement allowance	$ 0	$ 7,313