CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement of Cash Flows [Abstract]
Net income	$ 4,779	$ 4,918
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	7,183	4,550
Unrealized gain on equity investment	(1,373)	0
Stock-based compensation	5,136	3,165
Deferred income taxes	(1,645)	280
Accretion of discount on marketable securities	23	(13)
Non-cash operating lease expense	1,272	433
Other	54	2
Changes in operating assets and liabilities:
Accounts receivable	68,557	46,440
Prepaid expenses and other current assets	2,054	(1,241)
Accounts payable	(58,588)	(40,912)
Accrued expenses	(6,822)	(4,284)
Operating lease liabilities	(1,177)	(522)
Other liabilities, non-current	(139)	(129)
Net cash provided by operating activities	19,314	12,687
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(148)	(262)
Capitalized software development costs	(4,235)	(3,018)
Purchases of marketable securities	(39,422)	(23,168)
Proceeds from maturities of marketable securities	16,000	9,600
Net cash used in investing activities	(27,805)	(16,848)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	481	451
Principal payments on finance lease obligations	(28)	0
Payments for offering costs	0	(805)
Payments to acquire treasury stock	0	(27)
Net cash provided by (used in) financing activities	453	(381)
NET DECREASE IN CASH AND CASH EQUIVALENTS	(8,038)	(4,542)
CASH AND CASH EQUIVALENTS - Beginning of period	82,505	81,188
CASH AND CASH EQUIVALENTS - End of period	74,467	76,646
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Income taxes paid	323	192
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION:
Stock-based compensation capitalized as internal use software costs	333	153
Property and equipment included in accounts payable and accrued expenses	334	946
Capitalized software costs included in accounts payable and accrued expenses	516	270
Operating lease right-of-use assets obtained in exchange for new lease obligations	$ 4,632	$ 3,180