v3.20.1
Income taxes - Reconciliation of Income tax (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Jan. 31, 2020
Oct. 31, 2019
Jul. 31, 2019
Apr. 30, 2019
Jan. 31, 2019
Oct. 31, 2018
Jul. 31, 2018
Apr. 30, 2018
Jan. 31, 2020
Jan. 31, 2019
Jan. 31, 2018
Income Tax Disclosure [Abstract]                      
Federal income tax expense at the statutory rate                 $ 9,063 $ 15,922 $ 17,744
State income tax expense, net of federal tax benefit                 960 1,518 1,241
Other non-deductible or non-taxable items, net                 798 251 143
Excessive employee remuneration                 2,117 160 0
Excess tax benefits on stock-based compensation expense, net                 (4,815) (14,255) (14,136)
Federal research and development credits                 (2,296) (2,252) (729)
Change in uncertain tax position reserves, net of indirect benefits                 491 450 191
Non-deductible acquisition-related costs                 3,032 0 0
Non-taxable gain on investment in subsidiary                 (5,790) 0 0
Deferred tax rate adjustment due to tax reform                 0 0 458
Current statutory rate differential due to tax reform                 0 0 308
Other items, net                 (69) 125 223
Total income tax provision $ (417) $ (9,918) $ 4,370 $ 9,456 $ 3,241 $ 1,745 $ (1,029) $ (2,038) $ 3,491 $ 1,919 $ 4,827