Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
OPERATING ACTIVITIES
Net income	$ 4,971	$ 15,166
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Deferred tax benefit	(5,155)	(3,370)
Non-cash interest expense		19
Depreciation and amortization	364	422
Stock-based compensation expense	24,500	5,034
Bad debt expense	2,281	2,518
Changes in operating assets and liabilities:
Accounts receivable	(65,845)	(43,520)
Prepaid expenses and other current assets	(664)	1,046
Accounts payable	23,171	13,797
Accrued expenses and other current liabilities	6,489	9,413
Other noncurrent assets and liabilities	(1,374)	7
Net cash (used in) provided by operating activities	(11,262)	532
INVESTING ACTIVITIES
Purchase of property and equipment, net	(790)	(369)
Purchases of marketable securities	(59,867)	(62,146)
Sale of marketable securities	21,099	23,995
Net cash used in investing activities	(39,558)	(38,520)
FINANCING ACTIVITIES
Proceeds from exercise of stock options	830	539
Payment of employee taxes related to equity awards	(2,988)	(3,523)
Proceeds from contributions to employee stock purchase plan	386	487
Net cash used in financing activities	(1,772)	(2,497)
Net decrease in cash and cash equivalents	(52,592)	(40,485)
Cash and cash equivalents, beginning of period	91,413	70,305
Cash and cash equivalents, end of period	38,821	29,820
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid for income taxes, net of refunds received	5
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Additions of property and equipment, net included in accounts payable and accrued expenses	$ 251	$ 20