Condensed Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Stock-based expenses	$ 1,785	$ 1,283	$ 997
Partial release of valuation allowance		612	2
Cost of revenues
Amortization of intangibles acquired through business combinations	440	215	166
Stock-based expenses	204	161	130
Research and development
Stock-based expenses	510	307	260
Marketing and sales
Amortization of intangibles acquired through business combinations	352	232	121
Stock-based expenses	852	643	469
General and administrative
Stock-based expenses	$ 219	$ 172	$ 138