Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Jan. 31, 2019	Jan. 31, 2018
Deferred tax assets:
Net operating loss carryforwards	$ 189,117	$ 127,621
Tax credit carryover	50,848	33,105
Accruals and reserves	12,506	1,809
Deferred revenue	43,579	38,816
Stock-based compensation expense	31,743	24,133
Depreciation and amortization	19,578	15,367
Charitable contribution carryforwards	2,850	2,892
Other	81	465
Total deferred tax assets	350,302	244,208
Valuation allowance	(307,475)	(221,930)
Total deferred tax assets, net of valuation allowance	42,827	22,278
Deferred tax liabilities:
Deferred commissions	(27,537)	(21,218)
Convertible debt	(14,230)	0
Total deferred tax liabilities	(41,767)	(21,218)
Net deferred tax assets, net of valuation allowance	$ 1,060	$ 1,060