Basis of Presentation and Summary of Significant Accounting Policies - Recently Adopted Accounting Pronouncements (Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
Revenue:
Total revenue	$ 255,945	$ 182,645	[1]
As Previously Reported
Revenue:
Total revenue		182,631
Adjustment | Accounting Standards Update 2014-09
Revenue:
Total revenue		14
United States
Revenue:
Total revenue	184,918	146,505
United States | As Previously Reported
Revenue:
Total revenue		146,494
United States | Adjustment | Accounting Standards Update 2014-09
Revenue:
Total revenue		11
Rest of the world
Revenue:
Total revenue	$ 71,027	36,140
Rest of the world | As Previously Reported
Revenue:
Total revenue		36,137
Rest of the world | Adjustment | Accounting Standards Update 2014-09
Revenue:
Total revenue		$ 3

[1] * Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.