Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net loss	$ (15,283)	$ (10,354)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	9,731	6,560
Depreciation and amortization	4,091	3,681
Deferred tax expense	62	39
Non-cash operating lease costs	1,956	1,054
Non-cash change in earnout liabilities	(2,509)	0
Non-cash bad debt expense	631	222
Other	192	58
Changes in operating assets and liabilities:
Trade accounts receivable	(2,750)	(5,535)
Prepaid expenses and other current assets	(4,745)	(1,705)
Deferred commissions	(2,250)	(5,266)
Other noncurrent assets	(384)	(236)
Trade payables	3,659	3,590
Accrued expenses	(18,568)	(10,373)
Deferred revenue	4,128	9,031
Operating lease liabilities	(2,230)	(1,187)
Net cash used in operating activities	(24,269)	(10,421)
Cash flows from investing activities:
Purchase of property and equipment	(1,600)	(2,114)
Cash paid for acquisitions of businesses	0	(17,310)
Cash paid for acquired intangible assets	0	(131)
Net increase in customer fund assets	(3,915)	(7,224)
Net cash used in investing activities	(5,515)	(26,779)
Cash flows from financing activities:
Payments of deferred financing costs	0	(39)
Proceeds from exercise of stock options and common stock warrants	7,928	27,311
Proceeds from purchases of stock under employee stock purchase plan	5,716	7,664
Taxes paid related to net share settlement of stock-based awards	0	(93)
Payment related to business combination earnouts	(3,760)	0
Payment related to asset acquisition earnouts	(65)	0
Net increase in customer fund obligations	3,915	7,143
Net cash provided by financing activities	13,734	41,986
Foreign currency effect on cash and cash equivalents	(365)	(230)
Net change in cash and cash equivalents	(16,415)	4,556
Cash and cash equivalents—Beginning of period	466,950	142,322
Cash and cash equivalents—End of period	450,535	146,878
Supplemental cash flow disclosures:
Cash paid for interest expense	0	63
Cash paid for operating lease liabilities	3,108	2,110
Cash paid for income taxes	320	77
Non-cash investing and financing activities:
Stock issued related to business combinations	3,750	0
Accrued purchase price related to acquisitions	0	2,984
Accrued value of earnout related to acquisitions of businesses	0	5,952
Property and equipment additions in accounts payable and accrued expenses	743	938
Deferred financing costs in accounts payable and accrued expenses	0	272
Fair value of common stock issued to purchase intangible assets	87	50
Operating lease right-of-use assets in exchange for lease obligations	$ 6,562	$ 2,388