Intangible assets and goodwill (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Capitalized software development costs	$ 4,000,000.0	$ 2,100,000	$ 7,700,000	$ 4,200,000
Software development costs incurred and expensed	3,800,000	3,400,000	7,700,000	6,600,000
Amortization expense	4,000,000.0	3,500,000	7,900,000	7,200,000
Change in goodwill	0	$ 0	$ 0	$ 0
Intangible member assets
Finite-Lived Intangible Assets [Line Items]
Purchase price adjustment of acquired intangible members assets	$ 6,500,000
Useful life of intangible assets			15 years