Revenue Recognition - Deferred Contract Acquisition Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2020	Jan. 31, 2019
Capitalized Contract Cost, Net
Beginning balance	$ 55,516	$ 30,586
Additions to deferred contract acquisition costs	72,715	45,769
Amortization of deferred contract acquisition costs	(37,101)	(20,839)	$ (9,023)
Ending balance	91,130	55,516	30,586
Deferred contract acquisition costs, current				$ 44,885	$ 26,453
Deferred contract acquisition costs, noncurrent				46,245	29,063
Total deferred contract acquisition costs	$ 91,130	$ 55,516	$ 30,586	$ 91,130	$ 55,516