Deferred Commissions (Details) - USD ($)	3 Months Ended		9 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Revenue from Contract with Customer [Abstract]
Sales commissions capitalized as contract costs	$ 21,500,000	$ 15,300,000	$ 51,800,000	$ 36,700,000
Amortization of contract costs	10,300,000	7,300,000	28,400,000	20,500,000
Impairment loss related to costs capitalized	$ 0	$ 0	$ 0	$ 0