Information about Geographic Areas - Revenues by Geographic Area (Detail) - USD ($) $ in Thousands	3 Months Ended									12 Months Ended
	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	[1]	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
Revenues by geography
Total revenues	$ 232,323	$ 224,731	$ 209,609	$ 195,547	$ 185,984		$ 177,008	$ 167,795	$ 159,772	$ 862,210	$ 690,559	$ 550,542
North America [Member]
Revenues by geography
Total revenues										480,713	377,797	299,056
Europe and other [Member]
Revenues by geography
Total revenues										236,100	188,542	164,416
Asia Pacific [Member]
Revenues by geography
Total revenues										$ 145,397	$ 124,220	$ 87,070

[1] See note 1 of the notes to the consolidated financial statements for a summary of adjustments.