CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows used in operating activities:
Net loss	$ (29,603)	$ (30,150)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	11,228	11,563
Allowance for doubtful accounts	1,247	783
Stock-based compensation	18,315	13,523
Deferred income taxes	(2,820)	(2,672)
Accretion of interest	6,859	6,060
Changes in operating assets and liabilities:
Accounts receivable	(17,219)	(8,251)
Prepaid expenses and other current assets	101	350
Other assets	137	30
Accounts payable	(502)	(28)
Accrued expenses and other current liabilities	21,565	14,530
Accrued compensation	(13,798)	(11,737)
Operating lease liabilities	(1,287)	(479)
Other liabilities	(543)	(1,414)
Net cash used in operating activities	(6,320)	(7,892)
Cash flows provided by (used in) investing activities:
Purchase of property and equipment	(962)	(571)
Purchase of internal-use software	(1,966)	(1,099)
Proceeds from marketable securities	0	9,000
Sale of assets	0	6
Acquisition of business, net of cash acquired	(9,000)	0
Net cash (used in) provided by investing activities	(11,928)	7,336
Cash flows provided by financing activities:
Net proceeds from the exercise of stock options	14,889	8,854
Cash received for withholding taxes on stock-based compensation, net	164	1,848
Net cash provided by financing activities	15,053	10,702
Net (decrease) increase in cash and cash equivalents	(3,195)	10,146
Foreign exchange difference	(3,202)	(177)
Cash and cash equivalents at beginning of the period	514,353	423,989
Cash and cash equivalents at end of the period	507,956	433,958
Income taxes paid	0	23
Interest paid	$ 0	$ 0