CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
OPERATING ACTIVITIES:
Net income (loss)	$ (14,598)	$ 22,642
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	12,350	10,011
Stock-based compensation	124,895	52,354
Allowance for credit losses on accounts receivable	725	203
Noncash lease expense	10,515	9,451
Deferred income taxes	(5,304)
Other	998	4,905
Changes in operating assets and liabilities:
Accounts receivable	259,483	208,847
Prepaid expenses and other assets	23,743	(16,180)
Accounts payable	(245,937)	(200,578)
Accrued expenses and other liabilities	(8,688)	(5,691)
Operating lease liabilities	(11,990)	(10,894)
Net cash provided by operating activities	146,192	75,070
INVESTING ACTIVITIES:
Purchases of investments	(121,221)	(89,354)
Sales of investments		4,539
Maturities of investments	64,133	62,670
Purchases of property and equipment	(8,401)	(13,120)
Capitalized software development costs	(1,614)	(1,062)
Net cash used in investing activities	(67,103)	(36,327)
FINANCING ACTIVITIES:
Proceeds from exercise of stock options	24,408	12,621
Taxes paid related to net settlement of restricted stock awards	(13,428)	(17,080)
Net cash provided by (used in) financing activities	10,980	(4,459)
Increase in cash and cash equivalents	90,069	34,284
Cash and cash equivalents—Beginning of period	754,154	437,353
Cash and cash equivalents—End of period	844,223	471,637
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid for operating lease liabilities	14,030	15,107
Asset retirement obligation		625
Operating lease assets obtained in exchange for operating lease liabilities	4,732	(937)
Capitalized assets financed by accounts payable	1,837	2,421
Stock-based compensation included in capitalized software development costs	$ 520	$ 631