Note 4 - Fair Value Measurements - Financial Assets and Liabilities (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Apr. 30, 2020	Jan. 31, 2020
Fair Value, Inputs, Level 1 [Member]
Liability related to the interest rate swap
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Cash and cash equivalents	112,299	107,319
Fair Value, Inputs, Level 1 [Member] | Certificates of Deposit [Member]
Cash and cash equivalents	10,114	14,917
Fair Value, Inputs, Level 2 [Member]
Liability related to the interest rate swap	(483)	(232)
Fair Value, Inputs, Level 2 [Member] | Money Market Funds [Member]
Cash and cash equivalents
Fair Value, Inputs, Level 2 [Member] | Certificates of Deposit [Member]
Cash and cash equivalents