CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020
Cash flows from operating activities
Net income	$ 105,869	$ 96,959	$ 330,294	$ 277,080
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	6,899	7,525	20,407	22,720
Reduction of operating lease right-of-use assets	2,855	3,322	8,556	9,411
Accretion of discount on short-term investments	1,574	1,203	4,859	1,688
Stock-based compensation	62,045	48,973	172,919	135,246
Amortization of deferred costs	6,597	5,350	19,426	15,425
Deferred income taxes	(2,021)	(1,894)	10,174	(3,532)
Loss (gain) on foreign currency from mark-to-market derivative	(65)	19	368	14
Bad debt (recovery) expense	58	(181)	195	(60)
Changes in operating assets and liabilities:
Accounts receivable	72,147	37,448	352,470	206,214
Unbilled accounts receivable	(16,870)	(16,585)	(20,764)	(20,418)
Deferred costs	(3,353)	(6,177)	(11,445)	(15,312)
Prepaid expenses and other current and long-term assets	4,407	8,195	3,278	(2,937)
Accounts payable	4,028	3,060	2,265	(456)
Accrued expenses and other current liabilities	(537)	1,541	8,646	4,357
Income taxes payable	12,010	4,538	11,993	(453)
Deferred revenue	(141,083)	(90,291)	(199,042)	(137,980)
Operating lease liabilities	(2,941)	(3,229)	(8,602)	(8,496)
Other long-term liabilities	1,340	(4,373)	4,412	384
Net cash provided by operating activities	112,959	95,403	710,409	482,895
Cash flows from investing activities
Purchases of short-term investments	(256,008)	(417,898)	(935,626)	(874,465)
Maturities and sales of short-term investments	248,093	158,628	657,062	528,194
Acquisitions, net of cash acquired	0	0	(2,133)	0
Long-term assets	(2,314)	(3,316)	(10,295)	(8,456)
Net cash used in investing activities	(10,229)	(262,586)	(290,992)	(354,727)
Cash flows from financing activities
Changes in lease liabilities - finance leases	0	79	(384)	(420)
Proceeds from exercise of common stock options	5,368	6,186	43,310	25,245
Taxes paid related to net share settlement of equity awards	(21,414)	0	(36,510)	0
Net cash (used in) provided by financing activities	(16,046)	6,265	6,416	24,825
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	(1,469)	(599)	(4,414)	2,683
Net change in cash, cash equivalents, and restricted cash	85,215	(161,517)	421,419	155,676
Cash, cash equivalents, and restricted cash at beginning of period	1,067,916	796,990	731,712	479,797
Cash, cash equivalents, and restricted cash at end of period	1,153,131	635,473	1,153,131	635,473
Cash, cash equivalents, and restricted cash at end of period:
Cash and cash equivalents	1,149,946	634,265	1,149,946	634,265
Restricted cash included in other long-term assets	3,185	1,208	3,185	1,208
Cash, cash equivalents, and restricted cash at end of period	1,153,131	635,473	1,153,131	635,473
Supplemental disclosures of other cash flow information:
Cash paid for income taxes, net of refunds	14,167	2,198	34,668	17,153
Excess tax benefits from employee stock plans	10,404	17,329	45,464	59,067
Non-cash investing activities:
Changes in accounts payable and accrued expenses related to property and equipment purchases	$ (223)	$ 697	$ (2,024)	$ 1,471