Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (25,385)	$ (14,134)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	6,656	3,705
Amortization of deferred costs	2,922	1,598
Deferred income taxes	(1,246)	41
Accretion of interest on convertible senior notes	5,436	1,201
Provision for credit losses and sales reserve	925	148
Stock-based compensation	10,310	7,785
Other non-cash adjustments		(189)
Changes in operating assets and liabilities:
Accounts receivable	445	5,543
Prepaid expenses	(3,057)	(4,233)
Deferred costs	(4,720)	(2,227)
Other assets	(4,069)	2,153
Accounts payable	(1,072)	4,112
Accrued payroll and employee related liabilities	3,221	1,205
Accrued expenses	1,732	(1,065)
Deferred revenue	5,118	2,767
Other liabilities	3,585	277
Net cash provided by operating activities	801	8,687
Cash flows from investing activities:
Capital expenditures	(524)	(2,773)
Payments for acquisition of business, net of acquired cash	(34,941)
Additions to capitalized software development costs	(2,004)	(2,018)
Purchase of short-term investments		(1,975)
Maturities of short-term investments		24,750
Net cash provided by (used in) investing activities	(37,469)	17,984
Cash flows from financing activities:
Proceeds from public offering, net of costs		139,115
Proceeds from employee stock purchase plan	1,710	1,283
Proceeds from stock option exercises	2,989	8,746
Other	(531)	(506)
Net cash provided by financing activities	4,168	148,638
Effect of exchange rates on cash, cash equivalents and restricted cash	(666)	(28)
Net increase (decrease) in cash, cash equivalents and restricted cash	(33,166)	175,281
Cash, cash equivalents and restricted cash—beginning of period	539,662	60,068	$ 60,068
Cash, cash equivalents and restricted cash—end of period	506,496	235,349	$ 539,662
Supplemental disclosures of cash flow information:
Taxes, net of refunds received	184
Supplemental disclosure of non-cash activities:
Capitalized assets included in accounts payable and accrued expenses	226	689
Capitalized development costs included in accounts payable and accrued expenses	13	16
Common stock issued in connection with acquisitions	30,434
Contingent consideration in connection with acquisitions	2,530
Purchase accounting payable, net	464
Stock-based compensation capitalized for software development	$ 58	$ 64