CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2021	Jul. 31, 2020
Cash flows from operating activities
Net income	$ 108,858	$ 93,551	$ 224,425	$ 180,121
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	6,880	7,317	13,508	15,195
Reduction of operating lease right-of-use assets	2,874	3,092	5,701	6,089
Accretion of discount on short-term investments	1,743	496	3,285	485
Stock-based compensation	62,385	49,366	110,874	86,273
Amortization of deferred costs	6,474	5,324	12,829	10,075
Deferred income taxes	6,953	(504)	12,195	(1,638)
Loss (gain) on foreign currency from mark-to-market derivative	2	(98)	433	(5)
Bad debt (recovery) expense	(22)	514	137	121
Changes in operating assets and liabilities:
Accounts receivable	(21,409)	14,606	280,323	168,766
Unbilled accounts receivable	267	619	(3,894)	(3,833)
Deferred costs	(3,802)	(5,793)	(8,092)	(9,135)
Income taxes payable	(3,726)	(3,141)	(17)	(4,991)
Prepaid expenses and other current and long-term assets	(3,866)	(11,683)	(1,129)	(11,132)
Accounts payable	5,031	914	(1,763)	(3,516)
Accrued expenses and other current liabilities	2,216	125	9,183	2,816
Deferred revenue	(49,783)	(49,166)	(57,959)	(47,689)
Operating lease liabilities	(2,913)	(2,456)	(5,661)	(5,267)
Other long-term liabilities	903	2,237	3,072	4,757
Net cash provided by operating activities	119,065	105,320	597,450	387,492
Cash flows from investing activities
Purchases of short-term investments	(422,680)	(267,749)	(679,618)	(456,567)
Maturities and sales of short-term investments	187,324	229,224	408,969	369,566
Acquisitions, net of cash acquired	(2,133)	0	(2,133)	0
Long-term assets	(5,325)	(5,407)	(7,981)	(5,140)
Net cash used in investing activities	(242,814)	(43,932)	(280,763)	(92,141)
Cash flows from financing activities
Changes in lease liabilities - finance leases	(98)	(251)	(384)	(499)
Proceeds from exercise of common stock options	20,851	9,278	37,942	19,059
Taxes paid related to net share settlement of equity awards	(15,096)	0	(15,096)	0
Net cash provided by financing activities	5,657	9,027	22,462	18,560
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	(180)	2,734	(2,945)	3,282
Net change in cash, cash equivalents, and restricted cash	(118,272)	73,149	336,204	317,193
Cash, cash equivalents, and restricted cash at beginning of period	1,186,188	723,841	731,712	479,797
Cash, cash equivalents, and restricted cash at end of period	1,067,916	796,990	1,067,916	796,990
Cash, cash equivalents, and restricted cash at end of period:
Cash and cash equivalents	1,064,731	795,782	1,064,731	795,782
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	1,067,916	796,990	1,067,916	796,990
Supplemental disclosures of other cash flow information:
Cash paid for income taxes, net of refunds	15,368	9,089	20,501	14,955
Excess tax benefits from employee stock plans	17,609	22,123	35,060	41,738
Non-cash investing activities:
Changes in accounts payable and accrued expenses related to property and equipment purchases	$ 104	$ 184	$ (2,826)	$ 774