CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Oct. 31, 2015	Oct. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 41,044,000	$ 33,580,000
Adjustments to reconcile net income to net cash (used in) provided by operating activities
Stock option compensation expense	1,708,000	1,489,000
Depreciation	444,000	423,000
Amortization of purchased intangibles	283,000	182,000
Deferred income tax expense (benefit)	988,000	(336,000)
Gain on the deconsolidation of a variable interest entity	(349,000)
Changes in operating assets and liabilities:
Accounts receivable	(8,072,000)	546,000
Costs and estimated earnings in excess of billings	323,000	213,000
Prepaid expenses and other assets	(1,604,000)	(308,000)
Accounts payable and accrued expenses	(4,702,000)	29,147,000
Billings in excess of costs and estimated earnings	(76,530,000)	21,423,000
Change in accumulated other comprehensive loss	(411,000)
Net cash (used in) provided by operating activities	(46,878,000)	86,359,000
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of short-term investments	(168,000,000)
Maturities of short-term investments	64,079,000
Purchase of APC, net of cash acquired (Note 2)	(4,210,000)
Purchases of property, plant and equipment	(2,671,000)	(1,842,000)
Loans to energy project developers	(931,000)	(614,000)
Net cash used in investing activities	(111,733,000)	(2,456,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the exercise of stock options	1,670,000	3,884,000
Excess income tax benefit on exercised stock options	88,000	1,025,000
Net cash provided by financing activities	1,758,000	4,909,000
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(156,853,000)	88,812,000
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	333,691,000	272,209,000
CASH AND CASH EQUIVALENTS, END OF PERIOD	176,838,000	361,021,000
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid for income taxes	$ 20,734,000	11,022,000
Common stock issued in connection with the acquisition of APC (noncash transaction, see Note 2)	3,536,000
Cash dividends declared, payable in November 2015 and 2014, respectively (noncash transaction, see Note 12)	$ 10,379,000	$ 10,166,000