CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 12,393	$ 9,454	$ 36,029	$ 14,260
Adjustments to reconcile net income to net cash provided by operating activities
Lease expense	1,100	500	3,017	1,318
Depreciation	819	940	2,560	2,798
Stock compensation expense	900	800	2,521	2,199
Amortization of purchased intangible assets	227	226	680	677
Deferred income tax expense			383	8,366
Other			390	593
Changes in operating assets and liabilities
Accounts receivable			(7,084)	6,585
Contract assets			16,727	6,156
Other assets			2,070	(15,976)
Accounts payable and accrued expenses			(19,966)	27,725
Contract liabilities			4,372	87,859
Net cash provided by operating activities			41,699	142,560
CASH FLOWS FROM INVESTING ACTIVITIES
Maturities of short-term investments			90,000	170,000
Purchases of short-term investments			(90,000)	(100,000)
Investment in solar energy projects			(4,085)
Purchases of property, plant and equipment			(1,123)	(1,412)
Net cash (used in) provided by investing activities			(5,208)	68,588
CASH FLOWS FROM FINANCING ACTIVITIES
Payments of cash dividends			(11,831)	(27,420)
Proceeds from the exercise of stock options			1,396	1,245
Net cash used in financing activities			(10,435)	(26,175)
EFFECTS OF EXCHANGE RATE CHANGES ON CASH			(1,164)	877
NET INCREASE IN CASH AND CASH EQUIVALENTS			24,892	185,850
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD			366,671	167,363
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 391,563	$ 353,213	$ 391,563	$ 353,213