CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								6 Months Ended		12 Months Ended
	Jul. 31, 2020	Apr. 30, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jan. 31, 2019	Jan. 31, 2018	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Revenue:
Total revenue	$ 327,874	$ 318,273	$ 346,767	$ 314,768	$ 299,876	$ 287,624	$ 335,360	$ 313,283			$ 1,307,682	$ 1,236,143	$ 1,155,457
Cost of revenue:
Total cost of revenue	66,971	72,294	75,223	72,201	68,963	75,077	85,982	74,106			286,689	304,128	386,030
Gross profit	260,903	245,979	271,544	242,567	230,913	212,547	249,378	239,177			1,020,993	932,015	769,427
Operating expenses:
Sales and marketing	264,453	299,162	304,936	291,838	253,843	245,703	213,707	196,497			1,160,389	909,750	649,657
Research and development	135,338	141,346	139,088	138,206	129,169	137,982	123,037	110,531			553,978	500,719	313,777
General and administrative	32,464	35,644	34,579	32,860	30,420	33,040	28,788	27,339			135,547	119,587	86,401
Total operating expenses	432,255	476,152	478,603	462,904	413,432	416,725	365,532	334,367			1,849,914	1,530,056	1,049,835
Loss from operations	(171,352)	(230,173)	(207,059)	(220,337)	(182,519)	(204,178)	(116,154)	(95,190)			(828,921)	(598,041)	(280,408)
Other expense, net	(9,757)	(5,640)	(5,863)	(5,040)	(4,705)	(3,212)	(4,399)	(2,703)			(26,300)	(15,019)	(9,306)
Loss before provision for income taxes	(181,109)	(235,813)	(212,922)	(225,377)	(187,224)	(207,390)	(120,553)	(97,893)			(855,221)	(613,060)	(289,714)
Provision for income taxes	4,239	4,858	4,642	3,923	7,114	2,423	2,210	(3,628)		$ 7,447	17,662	8,119	7,447
Net loss	$ (185,348)	$ (240,671)	$ (217,564)	$ (229,300)	$ (194,338)	$ (209,813)	$ (122,763)	$ (94,265)			$ (872,883)	$ (621,179)	$ (297,161)
Net income (loss) per share attributable to common stockholders—basic and diluted (in dollars per share)	$ (0.93)	$ (1.23)	$ (1.13)	$ (1.21)	$ (1.04)	$ (1.15)	$ (0.68)	$ (0.54)	$ (3.43)	$ (1.81)	$ (4.48)	$ (3.43)	$ (1.81)
Weighted-average shares used in computing net income (loss) per share attributable to common stockholders—basic and diluted (in shares)											194,719	181,031	164,091
Product
Revenue:
Total revenue	$ 179,075	$ 180,756	$ 213,547	$ 192,444	$ 186,347	$ 184,794	$ 236,932	$ 224,346			$ 765,822	$ 832,419	$ 887,989
Cost of revenue:
Total cost of revenue	13,413	15,990	20,676	21,233	28,323	29,528	45,966	39,261			71,312	143,078	276,127
Support, entitlements and other services
Revenue:
Total revenue	148,799	137,517	133,220	122,324	113,529	102,830	98,428	88,937			541,860	403,724	267,468
Cost of revenue:
Total cost of revenue	$ 53,558	$ 56,304	$ 54,547	$ 50,968	$ 40,640	$ 45,549	$ 40,016	$ 34,845			$ 215,377	$ 161,050	$ 109,903