CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jul. 31, 2018	Jul. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 21,786	$ 48,067
Adjustments to reconcile net income to net cash (used in) provided by operating activities
Depreciation	1,567	1,210
Gain on the settlement of litigation (Note 9)	(1,400)
Deferred income tax expense (benefit)	924	(153)
Stock compensation expense	906	2,315
Amortization of purchased intangible assets	506	518
Change in accrued interest on short-term investments	432	(629)
Provision for uncollectible accounts	(135)	345
Other	(677)	206
Changes in operating assets and liabilities
Accounts receivable	(19,946)	2,999
Prepaid expenses and other assets	337	2,600
Accounts payable and accrued expenses	(18,659)	21,485
Changes in contracts in progress, net (Note 4)	(44,173)	(44,387)
Net cash (used in) provided by operating activities	(58,532)	34,576
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of short-term investments	(91,000)	(357,500)
Maturities of short-term investments	206,500	310,000
Purchases of property, plant and equipment	(5,365)	(2,802)
Change in notes receivable	225	(200)
Net cash provided by (used in) investing activities	110,360	(50,502)
CASH FLOWS FROM FINANCING ACTIVITIES
Cash dividends paid	(7,784)
Proceeds from the exercise of stock options	14	2,453
Distributions to joint venture partners		(1,229)
Net cash (used in) provided by financing activities	(7,770)	1,224
EFFECTS OF EXCHANGE RATE CHANGES ON CASH	(399)	729
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	43,659	(13,973)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	122,107	167,198
CASH AND CASH EQUIVALENTS, END OF PERIOD	165,766	153,225
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid for income taxes	2,333	$ 19,754
Cash paid for interest	$ 659