Financial Statements (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Jan. 31, 2019	Jan. 31, 2018
Assets:
Deferred commissions, current	$ 28,532		$ 29,244
Deferred commissions, non-current	84,725		85,729
Total deferred commissions	113,257	$ 86,044	114,973	$ 87,313
Liabilities:
Deferred revenue, current	283,160		266,584
Deferred revenue, non-current	281,070		269,336
Total deferred revenue	564,230	388,614	535,920	$ 374,102
Stockholders' equity:
Accumulated deficit	(1,182,285)		$ (1,081,949)
Statement of operations
Total revenue	326,700	255,945
Gross profit	216,387	166,315
Sales and marketing	166,626	122,367
Total operating expenses	313,811	228,189
Loss from operations	(97,424)	(61,874)
Loss before provision for income taxes	(99,240)	(62,873)
Net loss	$ (100,336)	$ (64,304)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.41)	$ (0.29)
Adjustments to reconcile net loss to net cash provided by operating activities:
Deferred commissions	$ 1,716	$ 1,269
Accrued compensation and other liabilities	(43,993)	(29,881)
Cash provided by operating activities	6,642	18,596
Net cash used in investing activities	(198,553)	(32,521)
Cash, cash equivalents and restricted cash, beginning of period	463,813	258,820
Cash, cash equivalents and restricted cash, end of period	303,478	751,639
Product
Statement of operations
Total revenue	238,741	195,449
Support subscription
Statement of operations
Total revenue	$ 87,959	$ 60,496