Costs and estimated earnings on uncompleted contracts Costs and estimated earnings on uncompleted contracts (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2014	Jan. 31, 2013
Costs incurred on uncompleted contracts
Costs incurred on uncompleted contracts	$ 52,064	$ 39,556
Estimated earnings	18,915	13,861
Earned revenue	70,979	53,417
Billings to date	71,725	52,772
Costs in excess of billings, net	(746)	645
Costs and estimated earnings in excess of billings on uncompleted contracts	1,476	1,630
Billings in excess of costs and estimated earnings on uncompleted contracts	$ (2,222)	$ (985)