CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 9,454	$ (4,561)	$ 14,260	$ (33,494)
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Deferred income tax expense (benefit)			8,366	(4,521)
Depreciation	940	899	2,798	2,610
Stock compensation expense	800	600	2,199	1,512
Lease expense	500	100	1,318	637
Amortization of purchased intangible assets	226	272	677	864
Changes in accrued interest on short-term investments			482	1,106
Impairment loss				2,072
Other			111	60
Changes in operating assets and liabilities
Accounts receivable			6,585	1,274
Contract assets			6,156	7,992
Other assets			(15,976)	(1,760)
Accounts payable and accrued expenses			27,725	(12,523)
Contract liabilities			87,859	50,072
Net cash provided by operating activities			142,560	15,901
CASH FLOWS FROM INVESTING ACTIVITIES
Maturities of short-term investments			170,000	164,000
Purchases of short-term investments			(100,000)	(75,000)
Purchases of property, plant and equipment			(1,412)	(6,308)
Net cash provided by investing activities			68,588	82,692
CASH FLOWS FROM FINANCING ACTIVITIES
Payments of cash dividends			(27,420)	(11,714)
Proceeds from the exercise of stock options			1,245	1,567
Net cash used in financing activities			(26,175)	(10,147)
EFFECTS OF EXCHANGE RATE CHANGES ON CASH			877	(282)
NET INCREASE IN CASH AND CASH EQUIVALENTS			185,850	88,164
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD			167,363	164,318
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 353,213	$ 252,482	$ 353,213	$ 252,482