Costs, Estimated Earnings and Billings on Uncompleted Contracts (Details) (USD $)	Apr. 30, 2013	Jan. 31, 2013
Aggregate amounts of costs incurred and earnings accrued on uncompleted contracts compared with billings for contracts
Costs incurred on uncompleted contracts	$ 289,733,000	$ 259,390,000
Estimated accrued earnings	59,482,000	48,724,000
Contracts Receivables, Gross	349,215,000	308,114,000
Less-Billings to date	409,638,000	380,295,000
Billings in excess of costs and estimated earnings on uncompleted contracts, net	60,423,000	72,181,000
Costs and estimated earnings in excess of billings	1,062,000	1,178,000
Billings in excess of costs and estimated earnings	61,485,000	73,359,000
Billings in excess of costs and estimated earnings on uncompleted contracts, net	$ 60,423,000	$ 72,181,000