CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Oct. 31, 2017	Oct. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 65,296	$ 56,645
Adjustments to reconcile net income to net cash (used in) provided by operating activities
Stock option compensation expense	3,573	1,774
Depreciation	1,936	1,444
Amortization of purchased intangible assets	776	752
Deferred income tax expense (benefit)	475	(1,693)
Other	(317)	(119)
Impairment loss		1,979
Changes in operating assets and liabilities
Accounts receivable	(31,453)	21,304
Prepaid expenses and other assets	758	(1,432)
Accounts payable and accrued expenses	5,600	50,099
Billings in excess of costs and estimated earnings, net	(69,383)	54,558
Net cash (used in) provided by operating activities	(22,739)	185,311
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of short-term investments	(462,500)	(375,000)
Maturities of short-term investments	485,000	214,000
Purchases of property, plant and equipment	(4,006)	(2,481)
Loans made under notes receivable	(200)
Net cash provided by (used in) investing activities	18,294	(163,481)
CASH FLOWS FROM FINANCING ACTIVITIES
Cash dividends paid	(15,548)	(15,260)
Proceeds from the exercise of stock options	2,781	10,988
Distributions to joint venture partners	(1,229)	(7,500)
Net cash used in financing activities	(13,996)	(11,772)
EFFECTS OF EXCHANGE RATE CHANGES ON CASH	951	(192)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(17,490)	9,866
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	167,198	160,909
CASH AND CASH EQUIVALENTS, END OF PERIOD	149,708	170,775
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid for income taxes	$ 36,922	$ 26,364