Intangible assets and goodwill (Schedule of finite-lived intangible assets) (Details) - USD ($) $ in Thousands	Jul. 31, 2019	Jan. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 149,806	$ 132,827
Accumulated amortization	(61,038)	(53,161)
Intangible assets, net	88,768	79,666
Capitalized software development costs
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	48,410	40,583
Software
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	6,430	4,252
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	2,882	2,882
Acquired intangible member assets
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 92,084	$ 85,110